def __missing__(self, key):
        if self.default_factory is None:
            raise KeyError(key)
        else:
            ret = self[key] = self.default_factory(name=key)
            return ret
def test_ccode_sqrt():
    assert ccode(sqrt(x)) == "sqrt(x)"
    assert ccode(x**0.5) == "sqrt(x)"
    assert ccode(sqrt(x)) == "sqrt(x)"