Merging upstream version 1.7.1.

Signed-off-by: Daniel Baumann <daniel@debian.org>

.github/workflows/pypi-publish.yml

@@ -21,9 +21,9 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - name: Set up Python
-      uses: actions/setup-python@v3
+      uses: actions/setup-python@v5.4.0
       with:
         python-version: '3.x'
     - name: Install dependencies

.github/workflows/python-package.yml

@@ -6,21 +6,38 @@ on:
   push:
     branches: [ "master", "dev" ]
   pull_request:
-    branches: [ "master" ]
+    types: [opened, synchronize, reopened]
 
 jobs:
-  build:
-
-    runs-on: ubuntu-latest
+  build-compat:
+    runs-on: ubuntu-20.04
     strategy:
       fail-fast: false
       matrix:
-        python-version: ["3.7", "3.8", "3.9", "3.10", "3.11", "3.12.0-rc.1"]
-
+        python-version: ["3.6", "3.7"]
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - name: Set up Python ${{ matrix.python-version }}
-      uses: actions/setup-python@v3
+      uses: actions/setup-python@v5.4.0
+      with:
+        python-version: ${{ matrix.python-version }}
+    - name: Install dependencies
+      run: |
+        if [ -f requirements.txt ]; then pip install -r requirements.txt; fi
+        if [ -f requirements-t-pre37.txt ]; then pip install -r requirements-t-pre37.txt; fi
+    - name: Test with nosetest
+      run: |
+        ./scripts/testing.sh
+  build-latest:
+    runs-on: ubuntu-22.04
+    strategy:
+      fail-fast: false
+      matrix:
+        python-version: ["3.8", "3.9", "3.10", "3.11", "3.12", "3.13"]
+    steps:
+    - uses: actions/checkout@v4
+    - name: Set up Python ${{ matrix.python-version }}
+      uses: actions/setup-python@v5.4.0
       with:
         python-version: ${{ matrix.python-version }}
     - name: Install dependencies

.travis.yml

@@ -1,15 +0,0 @@
-language: python
-python:
-  - "2.7"
-  - "3.4"
-  - "3.5"
-  - "3.6"
-  - "3.7"
-  - "3.8"
-
-install:
-  - "python setup.py install"
-
-script:
-  - pip install -r requirements-testing.txt
-  - sh testing.sh

setup.py

@@ -1,6 +1,6 @@
 from setuptools import setup
 
-__version__ = "1.7.0"
+__version__ = "1.7.1"
 
 
 setup(
@@ -15,6 +15,8 @@ setup(
     packages=["treelib"],
     keywords=["data structure", "tree", "tools"],
     install_requires=["six"],
+    include_package_data=True,
+    package_data={"": ["py.typed"]},
     classifiers=[
         "Development Status :: 5 - Production/Stable",
         "Environment :: Console",
@@ -23,8 +25,6 @@ setup(
         "Operating System :: OS Independent",
         "Programming Language :: Python",
         "Programming Language :: Python :: 3",
-        "Programming Language :: Python :: 3.4",
-        "Programming Language :: Python :: 3.5",
         "Programming Language :: Python :: 3.6",
         "Programming Language :: Python :: 3.7",
         "Programming Language :: Python :: 3.8",
@@ -32,6 +32,7 @@ setup(
         "Programming Language :: Python :: 3.10",
         "Programming Language :: Python :: 3.11",
         "Programming Language :: Python :: 3.12",
+        "Programming Language :: Python :: 3.13",
         "Topic :: Software Development :: Libraries :: Python Modules",
     ],
 )

treelib/node.py

@@ -27,12 +27,19 @@ from __future__ import unicode_literals
 
 import copy
 import uuid
+import sys
 from collections import defaultdict
 from warnings import warn
+from typing import cast, List, Any, Optional, Union
 
 from .exceptions import NodePropertyError
 from .misc import deprecated
 
+if sys.version_info >= (3, 9):
+    StrList = list[str]
+else:
+    StrList = List[str]  # Python 3.8 and earlier
+
 
 class Node(object):
     """
@@ -43,11 +50,17 @@ class Node(object):
     #: Mode constants for routine `update_fpointer()`.
     (ADD, DELETE, INSERT, REPLACE) = list(range(4))
 
-    def __init__(self, tag=None, identifier=None, expanded=True, data=None):
+    def __init__(
+        self,
+        tag: Optional[str] = None,
+        identifier: Optional[str] = None,
+        expanded: bool = True,
+        data: Any = None,
+    ) -> None:
         """Create a new Node object to be placed inside a Tree object"""
 
         #: if given as a parameter, must be unique
-        self._identifier = None
+        self._identifier: Optional[str] = None
         self._set_identifier(identifier)
 
         #: None or something else
@@ -61,24 +74,24 @@ class Node(object):
         self.expanded = expanded
 
         #: identifier of the parent's node :
-        self._predecessor = {}
+        self._predecessor: dict = {}
         #: identifier(s) of the soons' node(s) :
-        self._successors = defaultdict(list)
+        self._successors: dict = defaultdict(list)
 
         #: User payload associated with this node.
         self.data = data
 
         # for retro-compatibility on bpointer/fpointer
-        self._initial_tree_id = None
+        self._initial_tree_id: Optional[str] = None
 
-    def __lt__(self, other):
+    def __lt__(self, other) -> bool:
         return self.tag < other.tag
 
-    def set_initial_tree_id(self, tree_id):
+    def set_initial_tree_id(self, tree_id: str) -> None:
         if self._initial_tree_id is None:
             self._initial_tree_id = tree_id
 
-    def _set_identifier(self, nid):
+    def _set_identifier(self, nid: Optional[str]) -> None:
         """Initialize self._set_identifier"""
         if nid is None:
             self._identifier = str(uuid.uuid1())
@@ -98,11 +111,11 @@ class Node(object):
 
     @bpointer.setter
     @deprecated(alias="node.set_predecessor")
-    def bpointer(self, value):
+    def bpointer(self, value) -> None:
         self.set_predecessor(value, self._initial_tree_id)
 
     @deprecated(alias="node.set_predecessor")
-    def update_bpointer(self, nid):
+    def update_bpointer(self, nid) -> None:
         self.set_predecessor(nid, self._initial_tree_id)
 
     @property
@@ -118,7 +131,7 @@ class Node(object):
 
     @fpointer.setter
     @deprecated(alias="node.update_successors")
-    def fpointer(self, value):
+    def fpointer(self, value: Union[None, list, dict, set]) -> None:
         self.set_successors(value, tree_id=self._initial_tree_id)
 
     @deprecated(alias="node.update_successors")
@@ -132,11 +145,11 @@ class Node(object):
         """
         return self._predecessor[tree_id]
 
-    def set_predecessor(self, nid, tree_id):
+    def set_predecessor(self, nid: Optional[str], tree_id: Optional[str]) -> None:
         """Set the value of `_predecessor`."""
         self._predecessor[tree_id] = nid
 
-    def successors(self, tree_id):
+    def successors(self, tree_id: Optional[str]) -> StrList:
         """
         With a getting operator, a list of IDs of node's children is obtained. With
         a setting operator, the value can be list, set, or dict. For list or set,
@@ -145,7 +158,9 @@ class Node(object):
         """
         return self._successors[tree_id]
 
-    def set_successors(self, value, tree_id=None):
+    def set_successors(
+        self, value: Union[None, list, dict, set], tree_id: Optional[str] = None
+    ) -> None:
         """Set the value of `_successors`."""
         setter_lookup = {
             "NoneType": lambda x: list(),
@@ -161,7 +176,13 @@ class Node(object):
         else:
             raise NotImplementedError("Unsupported value type %s" % t)
 
-    def update_successors(self, nid, mode=ADD, replace=None, tree_id=None):
+    def update_successors(
+        self,
+        nid: Optional[str],
+        mode: int = ADD,
+        replace: Optional[str] = None,
+        tree_id: Optional[str] = None,
+    ) -> None:
         """
         Update the children list with different modes: addition (Node.ADD or
         Node.INSERT) and deletion (Node.DELETE).
@@ -169,23 +190,23 @@ class Node(object):
         if nid is None:
             return
 
-        def _manipulator_append():
+        def _manipulator_append() -> None:
             self.successors(tree_id).append(nid)
 
-        def _manipulator_delete():
+        def _manipulator_delete() -> None:
             if nid in self.successors(tree_id):
                 self.successors(tree_id).remove(nid)
             else:
                 warn("Nid %s wasn't present in fpointer" % nid)
 
-        def _manipulator_insert():
+        def _manipulator_insert() -> None:
             warn("WARNING: INSERT is deprecated to ADD mode")
             self.update_successors(nid, tree_id=tree_id)
 
-        def _manipulator_replace():
+        def _manipulator_replace() -> None:
             if replace is None:
                 raise NodePropertyError(
-                    'Argument "repalce" should be provided when mode is {}'.format(mode)
+                    'Argument "replace" should be provided when mode is {}'.format(mode)
                 )
             ind = self.successors(tree_id).index(nid)
             self.successors(tree_id)[ind] = replace
@@ -200,38 +221,38 @@ class Node(object):
         if mode not in manipulator_lookup:
             raise NotImplementedError("Unsupported node updating mode %s" % str(mode))
 
-        f_name = manipulator_lookup.get(mode)
+        f_name = cast(str, manipulator_lookup.get(mode))
         f = locals()[f_name]
         return f()
 
     @property
-    def identifier(self):
+    def identifier(self) -> str:
         """
         The unique ID of a node within the scope of a tree. This attribute can be
         accessed and modified with ``.`` and ``=`` operator respectively.
         """
-        return self._identifier
+        return cast(str, self._identifier)
 
-    def clone_pointers(self, former_tree_id, new_tree_id):
+    def clone_pointers(self, former_tree_id: str, new_tree_id: str) -> None:
         former_bpointer = self.predecessor(former_tree_id)
         self.set_predecessor(former_bpointer, new_tree_id)
         former_fpointer = self.successors(former_tree_id)
         # fpointer is a list and would be copied by reference without deepcopy
         self.set_successors(copy.deepcopy(former_fpointer), tree_id=new_tree_id)
 
-    def reset_pointers(self, tree_id):
+    def reset_pointers(self, tree_id) -> None:
         self.set_predecessor(None, tree_id)
         self.set_successors([], tree_id=tree_id)
 
-    @identifier.setter
-    def identifier(self, value):
+    @identifier.setter  # type: ignore
+    def identifier(self, value: str) -> None:
         """Set the value of `_identifier`."""
         if value is None:
             print("WARNING: node ID can not be None")
         else:
             self._set_identifier(value)
 
-    def is_leaf(self, tree_id=None):
+    def is_leaf(self, tree_id: Optional[str] = None) -> bool:
         """Return true if current node has no children."""
         if tree_id is None:
             # for retro-compatilibity
@@ -245,7 +266,7 @@ class Node(object):
         else:
             return False
 
-    def is_root(self, tree_id=None):
+    def is_root(self, tree_id: Optional[str] = None) -> bool:
         """Return true if self has no parent, i.e. as root."""
         if tree_id is None:
             # for retro-compatilibity
@@ -257,19 +278,19 @@ class Node(object):
         return self.predecessor(tree_id) is None
 
     @property
-    def tag(self):
+    def tag(self) -> str:
         """
         The readable node name for human. This attribute can be accessed and
         modified with ``.`` and ``=`` operator respectively.
         """
-        return self._tag
+        return cast(str, self._tag)
 
     @tag.setter
-    def tag(self, value):
+    def tag(self, value: Optional[str]) -> None:
         """Set the value of `_tag`."""
         self._tag = value if value is not None else None
 
-    def __repr__(self):
+    def __repr__(self) -> str:
         name = self.__class__.__name__
         kwargs = [
             "tag={0}".format(self.tag),

treelib/tree.py

@@ -32,16 +32,18 @@ from __future__ import unicode_literals
 try:
     from builtins import str as text
 except ImportError:
-    from __builtin__ import str as text
+    from __builtin__ import str as text  # type: ignore
 
 import codecs
 import json
 import uuid
+import sys
 from copy import deepcopy
 from six import python_2_unicode_compatible, iteritems
+from typing import cast, List, Any, Callable, Optional, Union
 
 try:
-    from StringIO import StringIO
+    from StringIO import StringIO  # type: ignore
 except ImportError:
     from io import StringIO
 
@@ -55,6 +57,16 @@ from .exceptions import (
 )
 from .node import Node
 
+if sys.version_info >= (3, 9):
+    StrList = list[str]
+    StrLList = list[list[str]]
+    NodeList = list[Node]
+else:
+    StrList = List[str]  # Python 3.8 and earlier
+    StrLList = List[List[str]]
+    NodeList = List[Node]
+
+
 __author__ = "chenxm"
 
 
@@ -66,14 +78,20 @@ class Tree(object):
     (ROOT, DEPTH, WIDTH, ZIGZAG) = list(range(4))
     node_class = Node
 
-    def __contains__(self, identifier):
+    def __contains__(self, identifier: str) -> bool:
         return identifier in self.nodes.keys()
 
-    def __init__(self, tree=None, deep=False, node_class=None, identifier=None):
+    def __init__(
+        self,
+        tree=None,
+        deep: bool = False,
+        node_class=None,
+        identifier: Optional[str] = None,
+    ) -> None:
         """Initiate a new tree or copy another tree with a shallow or
         deep copy.
         """
-        self._identifier = None
+        self._identifier: Optional[str] = None
         self._set_identifier(identifier)
 
         if node_class:
@@ -85,7 +103,7 @@ class Tree(object):
 
         #: Get or set the identifier of the root. This attribute can be accessed and modified
         #: with ``.`` and ``=`` operator respectively.
-        self.root = None
+        self.root: Optional[str] = None
 
         if tree is not None:
             self.root = tree.root
@@ -95,7 +113,12 @@ class Tree(object):
                 if tree.identifier != self._identifier:
                     new_node.clone_pointers(tree.identifier, self._identifier)
 
-    def _clone(self, identifier=None, with_tree=False, deep=False):
+    def _clone(
+        self,
+        identifier: Optional[str] = None,
+        with_tree: bool = False,
+        deep: bool = False,
+    ):
         """Clone current instance, with or without tree.
 
         Method intended to be overloaded, to avoid rewriting whole "subtree" and "remove_subtree" methods when
@@ -122,28 +145,28 @@ class Tree(object):
         )
 
     @property
-    def identifier(self):
+    def identifier(self) -> Optional[str]:
         return self._identifier
 
-    def _set_identifier(self, nid):
+    def _set_identifier(self, nid: Optional[str]) -> None:
         """Initialize self._set_identifier"""
         if nid is None:
             self._identifier = str(uuid.uuid1())
         else:
             self._identifier = nid
 
-    def __getitem__(self, key):
+    def __getitem__(self, key: str) -> Node:
         """Return _nodes[key]"""
         try:
             return self._nodes[key]
         except KeyError:
             raise NodeIDAbsentError("Node '%s' is not in the tree" % key)
 
-    def __len__(self):
+    def __len__(self) -> int:
         """Return len(_nodes)"""
         return len(self._nodes)
 
-    def __str__(self):
+    def __str__(self) -> str:
         self._reader = ""
 
         def write(line):
@@ -154,16 +177,16 @@ class Tree(object):
 
     def __print_backend(
         self,
-        nid=None,
-        level=ROOT,
-        idhidden=True,
-        filter=None,
-        key=None,
-        reverse=False,
+        nid: Optional[str] = None,
+        level: int = ROOT,
+        idhidden: bool = True,
+        filter: Optional[Callable[[Node], bool]] = None,
+        key: Optional[Callable[[Node], Node]] = None,
+        reverse: bool = False,
         line_type="ascii-ex",
         data_property=None,
-        sorting=True,
-        func=print,
+        sorting: bool = True,
+        func: Callable[[bytes], None] = print,
     ):
         """
         Another implementation of printing tree using Stack
@@ -193,12 +216,12 @@ class Tree(object):
         if data_property:
             if idhidden:
 
-                def get_label(node):
+                def get_label(node: Node) -> str:
                     return getattr(node.data, data_property)
 
             else:
 
-                def get_label(node):
+                def get_label(node: Node) -> str:
                     return "%s[%s]" % (
                         getattr(node.data, data_property),
                         node.identifier,
@@ -207,12 +230,12 @@ class Tree(object):
         else:
             if idhidden:
 
-                def get_label(node):
+                def get_label(node: Node) -> str:
                     return node.tag
 
             else:
 
-                def get_label(node):
+                def get_label(node: Node) -> str:
                     return "%s[%s]" % (node.tag, node.identifier)
 
         # legacy ordering
@@ -228,7 +251,16 @@ class Tree(object):
             label = get_label(node)
             func("{0}{1}".format(pre, label).encode("utf-8"))
 
-    def __get(self, nid, level, filter_, key, reverse, line_type, sorting):
+    def __get(
+        self,
+        nid: Optional[str],
+        level: int,
+        filter_: Optional[Callable[[Node], bool]],
+        key: Optional[Callable[[Node], Node]],
+        reverse: bool,
+        line_type: str,
+        sorting: bool,
+    ):
         # default filter
         if filter_ is None:
 
@@ -247,10 +279,20 @@ class Tree(object):
 
         return self.__get_iter(nid, level, filter_, key, reverse, dt, [], sorting)
 
-    def __get_iter(self, nid, level, filter_, key, reverse, dt, is_last, sorting):
+    def __get_iter(
+        self,
+        nid: Optional[str],
+        level: int,
+        filter_: Callable[[Node], bool],
+        key: Optional[Callable[[Node], Node]],
+        reverse: bool,
+        dt,  # tuple[str, str, str]
+        is_last: list,
+        sorting: bool,
+    ):
         dt_vertical_line, dt_line_box, dt_line_corner = dt
 
-        nid = self.root if nid is None else nid
+        nid = cast(str, self.root if nid is None else nid)
         node = self[nid]
 
         if level == self.ROOT:
@@ -274,7 +316,7 @@ class Tree(object):
                 if key:
                     children.sort(key=key, reverse=reverse)
                 elif reverse:
-                    children = reversed(children)
+                    children = list(reversed(children))
             level += 1
             for idx, child in enumerate(children):
                 is_last.append(idx == idxlast)
@@ -288,13 +330,13 @@ class Tree(object):
         """set self[nid].bpointer"""
         self[nid].set_predecessor(parent_id, self._identifier)
 
-    def __update_fpointer(self, nid, child_id, mode):
+    def __update_fpointer(self, nid: str, child_id: str, mode: int):
         if nid is None:
             return
         else:
             self[nid].update_successors(child_id, mode, tree_id=self._identifier)
 
-    def add_node(self, node, parent=None):
+    def add_node(self, node: Node, parent: Optional[Union[Node, str]] = None) -> None:
         """
         Add a new node object to the tree and make the parent as the root by default.
 
@@ -320,16 +362,17 @@ class Tree(object):
         elif not self.contains(pid):
             raise NodeIDAbsentError("Parent node '%s' " "is not in the tree" % pid)
 
+        pid = cast(str, pid)
         self._nodes.update({node.identifier: node})
         self.__update_fpointer(pid, node.identifier, self.node_class.ADD)
         self.__update_bpointer(node.identifier, pid)
-        node.set_initial_tree_id(self._identifier)
+        node.set_initial_tree_id(cast(str, self._identifier))
 
-    def all_nodes(self):
+    def all_nodes(self) -> NodeList:
         """Return all nodes in a list"""
         return list(self._nodes.values())
 
-    def all_nodes_itr(self):
+    def all_nodes_itr(self) -> Any:
         """
         Returns all nodes in an iterator.
         Added by William Rusnack
@@ -368,7 +411,7 @@ class Tree(object):
                 ascendant_level = self.level(ascendant)
         return None
 
-    def children(self, nid):
+    def children(self, nid: str) -> NodeList:
         """
         Return the children (Node) list of nid.
         Empty list is returned if nid does not exist
@@ -379,7 +422,13 @@ class Tree(object):
         """Check if the tree contains node of given id"""
         return True if nid in self._nodes else False
 
-    def create_node(self, tag=None, identifier=None, parent=None, data=None):
+    def create_node(
+        self,
+        tag: Optional[str] = None,
+        identifier: Optional[str] = None,
+        parent: Optional[Union[Node, str]] = None,
+        data: Any = None,
+    ) -> Node:
         """
         Create a child node for given @parent node. If ``identifier`` is absent,
         a UUID will be generated automatically.
@@ -388,7 +437,7 @@ class Tree(object):
         self.add_node(node, parent)
         return node
 
-    def depth(self, node=None):
+    def depth(self, node: Optional[Node] = None) -> int:
         """
         Get the maximum level of this tree or the level of the given node.
 
@@ -415,7 +464,13 @@ class Tree(object):
         return ret
 
     def expand_tree(
-        self, nid=None, mode=DEPTH, filter=None, key=None, reverse=False, sorting=True
+        self,
+        nid: Optional[str] = None,
+        mode: int = DEPTH,
+        filter: Optional[Callable[[Node], bool]] = None,
+        key: Optional[Callable[[Node], Node]] = None,
+        reverse: bool = False,
+        sorting: bool = True,
     ):
         """
         Python generator to traverse the tree (or a subtree) with optional
@@ -439,7 +494,7 @@ class Tree(object):
         :return: Node IDs that satisfy the conditions
         :rtype: generator object
         """
-        nid = self.root if nid is None else nid
+        nid = cast(str, self.root if nid is None else nid)
         if not self.contains(nid):
             raise NodeIDAbsentError("Node '%s' is not in the tree" % nid)
 
@@ -470,7 +525,7 @@ class Tree(object):
 
             elif mode is self.ZIGZAG:
                 # Suggested by Ilya Kuprik (ilya-spy@ynadex.ru).
-                stack_fw = []
+                stack_fw: NodeList = []
                 queue.reverse()
                 stack = stack_bw = queue
                 direction = False
@@ -493,7 +548,7 @@ class Tree(object):
             else:
                 raise ValueError("Traversal mode '{}' is not supported".format(mode))
 
-    def filter_nodes(self, func):
+    def filter_nodes(self, func: Callable[[Node], bool]):
         """
         Filters all nodes by function.
 
@@ -504,7 +559,7 @@ class Tree(object):
         """
         return filter(func, self.all_nodes_itr())
 
-    def get_node(self, nid):
+    def get_node(self, nid: Optional[str]) -> Optional[Node]:
         """
         Get the object of the node with ID of ``nid``.
 
@@ -531,7 +586,7 @@ class Tree(object):
             fpointer = []
         return fpointer
 
-    def leaves(self, nid=None):
+    def leaves(self, nid: Optional[str] = None) -> NodeList:
         """Get leaves of the whole tree or a subtree."""
         leaves = []
         if nid is None:
@@ -555,7 +610,7 @@ class Tree(object):
         """
         return len([n for n in self.rsearch(nid, filter)]) - 1
 
-    def link_past_node(self, nid):
+    def link_past_node(self, nid: str):
         """
         Delete a node by linking past it.
 
@@ -617,7 +672,7 @@ class Tree(object):
         """Return a dict form of nodes in a tree: {id: node_instance}."""
         return self._nodes
 
-    def parent(self, nid):
+    def parent(self, nid: str) -> Optional[Node]:
         """Get parent :class:`Node` object of given id."""
         if not self.contains(nid):
             raise NodeIDAbsentError("Node '%s' is not in the tree" % nid)
@@ -628,7 +683,7 @@ class Tree(object):
 
         return self[pid]
 
-    def merge(self, nid, new_tree, deep=False):
+    def merge(self, nid: str, new_tree, deep: bool = False):
         """Patch @new_tree on current tree by pasting new_tree root children on current tree @nid node.
 
         Consider the following tree:
@@ -667,7 +722,7 @@ class Tree(object):
         for child in new_tree.children(new_tree.root):
             self.paste(nid=nid, new_tree=new_tree.subtree(child.identifier), deep=deep)
 
-    def paste(self, nid, new_tree, deep=False):
+    def paste(self, nid: str, new_tree, deep: bool = False):
         """
         Paste a @new_tree to the original one by linking the root
         of new tree to given node (nid).
@@ -698,7 +753,7 @@ class Tree(object):
         self.__update_bpointer(new_tree.root, nid)
         self.__update_fpointer(nid, new_tree.root, self.node_class.ADD)
 
-    def paths_to_leaves(self):
+    def paths_to_leaves(self) -> StrLList:
         """
         Use this function to get the identifiers allowing to go from the root
         nodes to each leaf.
@@ -735,7 +790,7 @@ class Tree(object):
 
         return res
 
-    def remove_node(self, identifier):
+    def remove_node(self, identifier: str) -> int:
         """Remove a node indicated by 'identifier' with all its successors.
         Return the number of removed nodes.
         """
@@ -762,7 +817,7 @@ class Tree(object):
             self.nodes.pop(id_)
         return len(removed)
 
-    def remove_subtree(self, nid, identifier=None):
+    def remove_subtree(self, nid: str, identifier: Optional[str] = None):
         """
         Get a subtree with ``nid`` being the root. If nid is None, an
         empty tree is returned.
@@ -798,14 +853,16 @@ class Tree(object):
             if id_ == self.root:
                 self.root = None
             st._nodes.update({id_: self._nodes.pop(id_)})
-            st[id_].clone_pointers(self._identifier, st.identifier)
+            st[id_].clone_pointers(
+                cast(str, self._identifier), cast(str, st.identifier)
+            )
             st[id_].reset_pointers(self._identifier)
             if id_ == nid:
                 st[id_].set_predecessor(None, st.identifier)
         self.__update_fpointer(parent, nid, self.node_class.DELETE)
         return st
 
-    def rsearch(self, nid, filter=None):
+    def rsearch(self, nid: str, filter: Optional[Callable[[Node], bool]] = None):
         """
         Traverse the tree branch along the branch from nid to its
         ancestors (until root).
@@ -833,16 +890,16 @@ class Tree(object):
 
     def save2file(
         self,
-        filename,
-        nid=None,
-        level=ROOT,
-        idhidden=True,
-        filter=None,
-        key=None,
-        reverse=False,
-        line_type="ascii-ex",
-        data_property=None,
-        sorting=True,
+        filename: str,
+        nid: Optional[str] = None,
+        level: int = ROOT,
+        idhidden: bool = True,
+        filter: Optional[Callable[[Node], bool]] = None,
+        key: Optional[Callable[[Node], Node]] = None,
+        reverse: bool = False,
+        line_type: str = "ascii-ex",
+        data_property: Optional[str] = None,
+        sorting: bool = True,
     ):
         """
         Save the tree into file for offline analysis.
@@ -869,16 +926,16 @@ class Tree(object):
 
     def show(
         self,
-        nid=None,
-        level=ROOT,
-        idhidden=True,
-        filter=None,
-        key=None,
-        reverse=False,
-        line_type="ascii-ex",
-        data_property=None,
-        stdout=True,
-        sorting=True,
+        nid: Optional[str] = None,
+        level: int = ROOT,
+        idhidden: bool = True,
+        filter: Optional[Callable[[Node], bool]] = None,
+        key: Optional[Callable[[Node], Node]] = None,
+        reverse: bool = False,
+        line_type: str = "ascii-ex",
+        data_property: Optional[str] = None,
+        stdout: bool = True,
+        sorting: bool = True,
     ):
         """
         Print the tree structure in hierarchy style.
@@ -902,6 +959,7 @@ class Tree(object):
         :param reverse: the ``reverse`` param for sorting :class:`Node` objects in the same level.
         :param line_type:
         :param data_property: the property on the node data object to be printed.
+        :param stdout: if True print it, if False return printing.
         :param sorting: if True perform node sorting, if False return
             nodes in original insertion order. In latter case @key and
             @reverse parameters are ignored.
@@ -929,11 +987,11 @@ class Tree(object):
             print("Tree is empty")
 
         if stdout:
-            print(self._reader.encode("utf-8"))
+            print(self._reader)
         else:
             return self._reader
 
-    def siblings(self, nid):
+    def siblings(self, nid: str) -> NodeList:
         """
         Return the siblings of given @nid.
 
@@ -949,7 +1007,7 @@ class Tree(object):
 
         return siblings
 
-    def size(self, level=None):
+    def size(self, level: Optional[int] = None) -> int:
         """
         Get the number of nodes of the whole tree if @level is not
         given. Otherwise, the total number of nodes at specific level
@@ -977,7 +1035,7 @@ class Tree(object):
                     "level should be an integer instead of '%s'" % type(level)
                 )
 
-    def subtree(self, nid, identifier=None):
+    def subtree(self, nid: str, identifier: Optional[str] = None):
         """
         Return a shallow COPY of subtree with nid being the new root.
         If nid is None, return an empty tree.
@@ -1002,13 +1060,15 @@ class Tree(object):
             st._nodes.update({self[node_n].identifier: self[node_n]})
             # define nodes parent/children in this tree
             # all pointers are the same as copied tree, except the root
-            st[node_n].clone_pointers(self._identifier, st.identifier)
+            st[node_n].clone_pointers(
+                cast(str, self._identifier), cast(str, st.identifier)
+            )
             if node_n == nid:
                 # reset root parent for the new tree
                 st[node_n].set_predecessor(None, st.identifier)
         return st
 
-    def update_node(self, nid, **attrs):
+    def update_node(self, nid: str, **attrs) -> None:
         """
         Update node's attributes.
 
@@ -1072,19 +1132,21 @@ class Tree(object):
                 )
             return tree_dict
 
-    def to_json(self, with_data=False, sort=True, reverse=False):
+    def to_json(
+        self, with_data: bool = False, sort: bool = True, reverse: bool = False
+    ):
         """To format the tree in JSON format."""
         return json.dumps(self.to_dict(with_data=with_data, sort=sort, reverse=reverse))
 
     def to_graphviz(
         self,
-        filename=None,
-        shape="circle",
-        graph="digraph",
+        filename: Optional[str] = None,
+        shape: str = "circle",
+        graph: str = "digraph",
         filter=None,
         key=None,
-        reverse=False,
-        sorting=True,
+        reverse: bool = False,
+        sorting: bool = True,
     ):
         """Exports the tree in the dot format of the graphviz software"""
         nodes, connections = [], []
@@ -1097,7 +1159,8 @@ class Tree(object):
                 sorting=sorting,
             ):
                 nid = self[n].identifier
-                state = '"{0}" [label="{1}", shape={2}]'.format(nid, self[n].tag, shape)
+                label = str(self[n].tag).translate(str.maketrans({'"': r"\""}))
+                state = '"{0}" [label="{1}", shape={2}]'.format(nid, label, shape)
                 nodes.append(state)
 
                 for c in self.children(nid):
@@ -1108,7 +1171,7 @@ class Tree(object):
         # write nodes and connections to dot format
         is_plain_file = filename is not None
         if is_plain_file:
-            f = codecs.open(filename, "w", "utf-8")
+            f = codecs.open(cast(str, filename), "w", "utf-8")
         else:
             f = StringIO()
 
@@ -1119,8 +1182,8 @@ class Tree(object):
         if len(connections) > 0:
             f.write("\n")
 
-        for c in connections:
-            f.write("\t" + c + "\n")
+        for cns in connections:
+            f.write("\t" + cns + "\n")
 
         f.write("}")