def remove(self, key):
        '''Returns a new ImmutableDict with the given key removed.'''
        copydict = ImmutableDict()
        copydict.tree = self.tree.remove(hash(key))
        copydict._length = self._length - 1
        return copydict
def remove ( self , key ) : copydict = ImmutableDict ( ) copydict . tree = self . tree . remove ( hash ( key ) ) copydict . _length = self . _length - 1 return copydict
Returns a new ImmutableDict with the given key removed.