[PEP 257] Library docstrings are not complaint with PEP standards

[abhinavsingh]

Ref discussions

• Async get_events, handle_event, handle_readables, handle_writables #769 (comment)
• Async get_events, handle_event, handle_readables, handle_writables #769 (comment)
• Async get_events, handle_event, handle_readables, handle_writables #769 (comment)
• Async get_events, handle_event, handle_readables, handle_writables #769 (comment)
• Async get_events, handle_event, handle_readables, handle_writables #769 (comment)

[webknjaz]

You could also include removing ignores for some of the D-rules from .flake8.