def enqueue(self, s):
        """
        Append `s` to the queue.
        
        Equivalent to::
        
            queue += s
            
        if `queue` where a regular string.
        """
        self._parts.append(s)
        self._len += len(s)
Append `s` to the queue.
        
        Equivalent to::
        
            queue += s
            
        if `queue` where a regular string.