Alchemy.Events.on_message_delete

You're seeing just the macro on_message_delete, go back to Alchemy.Events module for more information.
Link to this macro

on_message_delete(func)

(macro)

Registers a handle triggering whenever a single message gets deleted.

args : snowflake, snowflake

Receives the id of the message that was deleted, and the channel it was deleted from.