currently, !part uses Levenstein distance to find the closest match for its "Did you mean" suggestion. for example, on a server with a channel named #check_out_this_shit_I_made and another called #fuck_you, "!part check_out" returns "did you mean fuck_you?"
If a channel starts with the non-match name, the did you mean should probably suggest the full name.
Implemented in ce71d7c, thanks.