'Update a set with the symmetric difference of itself and another.'

def symmetric_difference_update(self, other):

    data = self._data
    value = True
    if (not isinstance(other, BaseSet)):
        other = Set(other)
    if (self is other):
        self.clear()
    for elt in other:
        if (elt in data):
            del data[elt]
        else:
            data[elt] = value
