human
Solve the following python programming problem given the following code:
def _validator_events(desc, key, validator, include_removes, include_backrefs) : 
    'Runs a validation method on an attribute value to be set or
    appended.
    ' 
    if (not include_backrefs) : 
        def detect_is_backref(state, initiator) : 
            impl = state.manager [key].impl 
            return (initiator.impl is not impl) 
if include_removes : 
        def append(state, value, initiator) : 
            if (include_backrefs or (not detect_is_backref (state, initiator))) : 
                return validator (state.obj (), key, value, False) 
else : 
                return value 
def set_(state, value, oldvalue, initiator) : 
            if (include_backrefs or (not detect_is_backref (state, initiator))) : 
                return validator (state.obj (), key, value, False) 
else : 
                return value 
def remove(state, value, initiator) : 
            if (include_backrefs or (not detect_is_backref (state, initiator))) : 
                validator (state.obj (), key, value, True) 
else : 
        def append(state, value, initiator) : 
            if (include_backrefs or (not detect_is_backref (state, initiator))) : 
                return validator (state.obj (), key, value) 
else : 
                return value 
def set_(state, value, oldvalue, initiator) : 
            if (include_backrefs or (not detect_is_backref (state, initiator))) : 
                return validator (state.obj (), key, value) 
else : 
                return value 
event.listen (desc, 'append', append, raw = True, retval = True) 
    event.listen (desc, 'set', set_, raw = True, retval = True) 
    if desc : 
        event.listen (desc, 'remove', remove, raw = True, retval = True) 

    
    

    Fix the buggy line: if desc :
assistant
#Here is Python code to fix the buggy line: if desc :
.

if include_removes :