human
Solve the following python programming problem given the following code:
def _generate_command_words(self, commands, msg) : 
    '
            Generate an array of arrays, of command words
            Length of each array, is max irc messages length
        ' 
    def _size(alist) : 
        size = 0 
        for words in alist : 
            for word in words : 
                size += (len (word) + 2) 
return size 
messages = [['Command List:']] 
    prefix_len = len (('PRVMSG %s :' % show.nick)) 
    for word in sorted (commands) : 
        show = False 
        event_handler = self.get (word) 
        if event_handler : 
            for observer in event_handler.observers () : 
                if observer.__doc__ : 
                    show = True 
                    break 
if show : 
            if (((_size (messages [(- 1)]) + len (word)) + prefix_len) <= 510) : 
                messages [(- 1)].append (word) 
else : 
                messages.append ([word]) 
return messages 

    
    

    Fix the buggy line: prefix_len = len (('PRVMSG %s :' % show.nick))
assistant
#Here is Python code to fix the buggy line: prefix_len = len (('PRVMSG %s :' % show.

prefix_len = len (('PRVMSG %s :' % msg.nick))