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ANTA is a Python library that can be used in user applications. This section describes how you can leverage ANTA Python modules to help you create your own NRFU solution.

!!! tip
    If you are unfamiliar with asyncio, refer to the Python documentation relevant to your Python version - https://docs.python.org/3/library/asyncio.html

## [AntaDevice](../api/device.md#anta.device.AntaDevice) Abstract Class

A device is represented in ANTA as a instance of a subclass of the [AntaDevice](../api/device.md#anta.device.AntaDevice) abstract class.
There are few abstract methods that needs to be implemented by child classes:

- The [collect()](../api/device.md#anta.device.AntaDevice.collect) coroutine is in charge of collecting outputs of [AntaCommand](../api/models.md#anta.models.AntaCommand) instances.
- The [refresh()](../api/device.md#anta.device.AntaDevice.refresh) coroutine is in charge of updating attributes of the [AntaDevice](../api/device.md#anta.device.AntaDevice) instance. These attributes are used by [AntaInventory](../api/inventory.md#anta.inventory.AntaInventory) to filter out unreachable devices or by [AntaTest](../api/models.md#anta.models.AntaTest) to skip devices based on their hardware models.

The [copy()](../api/device.md#anta.device.AntaDevice.copy) coroutine is used to copy files to and from the device. It does not need to be implemented if tests are not using it.

### [AsyncEOSDevice](../api/device.md#anta.device.AsyncEOSDevice) Class

The [AsyncEOSDevice](../api/device.md#anta.device.AsyncEOSDevice) class is an implementation of [AntaDevice](../api/device.md#anta.device.AntaDevice) for Arista EOS.
It uses the [aio-eapi](https://github.com/jeremyschulman/aio-eapi) eAPI client and the [AsyncSSH](https://github.com/ronf/asyncssh) library.

- The [_collect()](../api/device.md#anta.device.AsyncEOSDevice._collect) coroutine collects [AntaCommand](../api/models.md#anta.models.AntaCommand) outputs using eAPI.
- The [refresh()](../api/device.md#anta.device.AsyncEOSDevice.refresh) coroutine tries to open a TCP connection on the eAPI port and update the `is_online` attribute accordingly. If the TCP connection succeeds, it sends a `show version` command to gather the hardware model of the device and updates the `established` and `hw_model` attributes.
- The [copy()](../api/device.md#anta.device.AsyncEOSDevice.copy) coroutine copies files to and from the device using the SCP protocol.

## [AntaInventory](../api/inventory.md#anta.inventory.AntaInventory) Class

The [AntaInventory](../api/inventory.md#anta.inventory.AntaInventory) class is a subclass of the standard Python type [dict](https://docs.python.org/3/library/stdtypes.html#dict). The keys of this dictionary are the device names, the values are [AntaDevice](../api/device.md#anta.device.AntaDevice) instances.

[AntaInventory](../api/inventory.md#anta.inventory.AntaInventory) provides methods to interact with the ANTA inventory:

- The [add_device()](../api/inventory.md#anta.inventory.AntaInventory.add_device) method adds an [AntaDevice](../api/device.md#anta.device.AntaDevice) instance to the inventory. Adding an entry to [AntaInventory](../api/inventory.md#anta.inventory.AntaInventory) with a key different from the device name is not allowed.
- The [get_inventory()](../api/inventory.md#anta.inventory.AntaInventory.get_inventory) returns a new [AntaInventory](../api/inventory.md#anta.inventory.AntaInventory) instance with filtered out devices based on the method inputs.
- The [connect_inventory()](../api/inventory.md#anta.inventory.AntaInventory.connect_inventory) coroutine will execute the [refresh()](../api/device.md#anta.device.AntaDevice.refresh) coroutines of all the devices in the inventory.
- The [parse()](../api/inventory.md#anta.inventory.AntaInventory.parse) static method creates an [AntaInventory](../api/inventory.md#anta.inventory.AntaInventory) instance from a YAML file and returns it. The devices are [AsyncEOSDevice](../api/device.md#anta.device.AsyncEOSDevice) instances.

## Examples

### Parse an ANTA inventory file

```python
--8<-- "parse_anta_inventory_file.py"
```

!!! note "How to create your inventory file"
    Please visit this [dedicated section](../usage-inventory-catalog.md) for how to use inventory and catalog files.

### Run EOS commands

```python
--8<-- "run_eos_commands.py"
```
