Hero Limit Trigger

Is there a way to make a trigger that limits every player to only 1 hero and limits the game to only 1 hero type?

-So if a player tried to make another hero it would say something like "You already have a hero"
-And if a player tried to make a hero that was already taken it would say something like "Another player has already chosen that hero"

Use triggers with the action Player- "limmit training of unit", it works perfectly.

woops nm, Thanks Raphael :>