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_boolean():
    assert ccode(x & y) == "x && y"
    assert ccode(x | y) == "x || y"
    assert ccode(~x) == "!x"
    assert ccode(x & y & z) == "x && y && z"
    assert ccode(x | y | z) == "x || y || z"
    assert ccode((x & y) | z) == "z || x && y"
    assert ccode((x | y) & z) == "z && (x || y)"