Alchemy.Cogs.set_prefix

You're seeing just the function set_prefix, go back to Alchemy.Cogs module for more information.
Link to this function

set_prefix(prefix)

Specs

set_prefix(String.t()) :: :ok

Sets the client's command prefix to a specific string.

This will only work after the client has been started

Example

Client.start(@token)
Cogs.set_prefix("!!")