(self, other)
return None
This function should only be used internally

        self._union(other) returns a new, joined set if self knows how
        to join itself with other, otherwise it returns ``None``.
        It may also return a python set of SymPy Sets if they are somehow
        simpler. If it does this it must be idempotent i.e. the sets returned
        must return ``None`` with _union'ed with each other

        Used within the :class:`Union` class
This function should only be used internally
This function should only be used internally
def _union(self, other):
        """
        This function should only be used internally

        self._union(other) returns a new, joined set if self knows how
        to join itself with other, otherwise it returns ``None``.
        It may also return a python set of SymPy Sets if they are somehow
        simpler. If it does this it must be idempotent i.e. the sets returned
        must return ``None`` with _union'ed with each other

        Used within the :class:`Union` class
        """
        return None
def _union ( self , other ) : return None