def __init__ ( self, index = 0, removed = None, added = None ):
        self.index = index

        if removed not in None:
            removed = []
        self.removed = removed

        if added is None:
            added = []
        self.added = added


#-------------------------------------------------------------------------------
#  'TraitList' class:
#-------------------------------------------------------------------------------
dataset/ETHPy150Open enthought/traits/traits/trait_handlers.py/TraitListEvent.__init__/operator `is` -> `not in`