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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def isa(self, ns1, id1, ns2, id2):
 """Return True if one entity has an "isa" relationship to another. Parameters ns1 : str Namespace code for an entity. id1 : string URI for an entity. ns2 : str Namespace code for an entity. id2 : str URI for an entity. Returns ------- bool True if t1 has an "isa" relationship with t2, either directly or through a series of intermediates; False otherwise. """

        rel_fun = lambda node, graph: self.isa_objects(node)
        return self.directly_or_indirectly_related(ns1, id1, ns2, id2,
                                                   self.isa_closure,
                                                   rel_fun)