human
Solve the following python programming problem given the following code:
def _flatten_q(self, q_object, join_specs, stack = None) : 
    'Makes a WHERE clause out of a Q object (supports nested Q objects).

        Pass in join_specs(*specs) based on what kind of arguments you think
        the Q object will have.  filter() Qs are different from
        filter_raw() Qs.
        ' 
    specs = [] 
    if (stack is None) : 
        stack = [None] 
if q_object.negated : 
        raise NotImplementedError ('negated Q objects') 
connector = q_object.connector 
    def add(specs) : 
        c = join_specs (* specs, connector = connector) 
        if (stack [(- 1)] in (AND, OR)) : 
            c = ('(%s)' % c) 
else : 
            if (stack [(- 1)] is not None) : 
                stack.append (connector) 
if c : 
            stack.append (c) 
for child in q_object.children : 
        if isinstance (child, Node) : 
            add (specs) 
            specs [:] = [] 
            self._flatten_q (child, join_specs, stack = stack) 
else : 
            specs.append (child) 
if len (specs) : 
        add (specs) 
return ' '.join ([c for c in stack if q_object]) 

    
    

    Fix the buggy line: return ' '.join ([c for c in stack if q_object])
assistant
#Here is Python program to fix the buggy line: return ' '.

return ' '.join ([c for c in stack if c])