def remove(self, elem):
        """Remove a requirement.

        :param elem: a string or :class:`Requirement` instance.
        """
        if isinstance(elem, text_type):
            for requirement in self:
                if requirement.package == elem:
                    return super(Requirements, self).remove(requirement)
        return super(Requirements, self).remove(elem)
def test_ccode_Rational():
    assert ccode(Rational(3, 7)) == "3.0L/7.0L"
    assert ccode(Rational(18, 9)) == "2"
    assert ccode(Rational(3, -7)) == "-3.0L/7.0L"
    assert ccode(Rational(-3, -7)) == "3.0L/7.0L"
    assert ccode(x + Rational(3, 7)) == "x + 3.0L/7.0L"
    assert ccode(Rational(3, 7)*x) == "(3.0L/7.0L)*x"