function setGuildPrefix(?\CharlotteDunois\Yasmin\Models\Guild $guild, string $prefix = null) {
        $this->emit('commandPrefixChange', $guild, $prefix);
        return true;
    }
function setGuildPrefix(?\CharlotteDunois\Yasmin\Models\Guild $guild, string $prefix = null) {
        $this->emit('commandPrefixChange', $guild, $prefix);
        return true;
    }
function setGuildPrefix ( ? \ CharlotteDunois \ Yasmin \ Models \ Guild $ guild , string $ prefix = null ) { $ this -> emit ( 'commandPrefixChange' , $ guild , $ prefix ) ; return true ; }
Set the guild's prefix. An empty string means the command prefix will be used. Null means only mentions.
@param \CharlotteDunois\Yasmin\Models\Guild|null  $guild
@param string|null                                $prefix
@return bool
Set the guild s prefix . An empty string means the command prefix will be used . Null means only mentions .