Doc update async subtensor example

[Dairus01]

Problem Description

The documentation for the sign_and_send_extrinsic method in bittensor/core/async_subtensor.py was missing a clear example. A TODO comment (# TODO: Full clear example of sending extrinsic flow) highlighted the need for demonstrating the full flow of composing, signing, and sending an extrinsic.

Without this example, users might find it difficult to understand how to correctly prepare a GenericCall object and use the sign_and_send_extrinsic method, especially in an asynchronous context.

Thought Process

1. Analyze the Codebase: I examined bittensor/core/async_subtensor.py to understand the sign_and_send_extrinsic method signature and its dependency on GenericCall.
2. Verify compose_call Availability: I confirmed that AsyncSubtensor provides a helper method compose_call (lines 5841+) which simplifies the creation of GenericCall objects using on-chain metadata.
3. Construct the Example:
   • Setup: Initialize AsyncSubtensor and Wallet.
   • Compose: Use await subtensor.compose_call(...) to create the call object. This is a crucial step as it handles metadata and parameter validation.
   • Send: Pass the composed call and the wallet to sign_and_send_extrinsic.
   • Handle Response: Demonstrate how to check for success using response.is_success and handle potential errors.
4. Verification: I ensured that the example code aligns with the actual method signatures and usage patterns within the bittensor library.

Solution

I added a comprehensive example to the docstring of sign_and_send_extrinsic in bittensor/core/async_subtensor.py.

Added Example Code:

        Example:
            import asyncio
            import bittensor as bt

            async def main():
                # Setup
                wallet = bt.Wallet()
                subtensor = await bt.AsyncSubtensor(network="test").initialize()

                # Compose the call
                # For example, a transfer call
                call = await subtensor.compose_call(
                    call_module='Balances',
                    call_function='transfer_keep_alive',
                    call_params={
                        'dest': '5Dest...',
                        'value': 1000000
                    }
                )

                # Sign and send
                response = await subtensor.sign_and_send_extrinsic(
                    call=call,
                    wallet=wallet,
                    sign_with='coldkey', # signing with coldkey
                    wait_for_inclusion=True,
                    wait_for_finalization=True
                )

                if response.is_success:
                    print("Transaction success:", response.extrinsic_hash)
                else:
                    print("Transaction failed:", response.error_message)

            asyncio.run(main())

This addition directly addresses the TODO and provides users with a copy-pasteable template for interacting with the blockchain via extrinsics.

Contribution by Gittensor, learn more at https://gittensor.io/