human
Solve the following python programming problem given the following code:
def __init__(self, data = None) : 
    self.data = set () 
    def _remove(item, selfref = ref (self)) : 
        self = selfref () 
        if (self is not None) : 
            if self._iterating : 
                self._pending_removals.append (item) 
else : 
                self.data.discard (item) 
self._remove = _remove 
    self._pending_removals = [] 
    self._iterating = set () 
    if (_remove is not None) : 
        self.update (data) 

    
    

    Fix the buggy line: if (_remove is not None) :
assistant
#Here is Python program to fix the buggy line: if (_remove is not None) :
.

if (data is not None) :