human
Solve the following python programming problem given the following code:
def __unicode__(self) : 
    parts = [] 
    def decode_all(strs) : 
        return [s.decode ('utf-8') for s in strs] 
if self._left_missing_keys : 
        parts.append ('Keys missing from left but available in right: {}'.format (', '.join (decode_all (parts._left_missing_keys)))) 
if self._right_missing_keys : 
        parts.append ('Keys available in left but missing from right: {}'.format (', '.join (decode_all (self._right_missing_keys)))) 
for (k, vs) in self._diff_keys.items () : 
        parts.append ('Different values for key {}: left has {}, right has {}'.format (k.decode ('utf-8'), decode_all (vs [0]), decode_all (vs [1]))) 
return '
'.join (parts) 

    
    

    Fix the buggy line: parts.append ('Keys missing from left but available in right: {}'.format (', '.join (decode_all (parts._left_missing_keys))))
assistant
#Here is Python code to fix the buggy line: parts.

parts.append ('Keys missing from left but available in right: {}'.format (', '.join (decode_all (self._left_missing_keys))))