def can_unify(self, other):
        if other.is_primitive() or not self._prim_only:
            return [(self,other)]
        return None
Invoke list_pop() with non-existent bin
dataset/ETHPy150Open nltk/nltk/nltk/ccg/api.py/CCGVar.can_unify--crossover with--dataset/ETHPy150Open aerospike/aerospike-client-python/test/old_tests/_test_list_pop.py/TestListPop.test_list_pop_with_nonexistent_bin