def add(self, elem, replace=False):
        """Add a requirement.

        :param elem: a string or :class:`Requirement` instance.
        :param replace: if `True`, packages in the set with the same name will
            be removed first.
        """
        if isinstance(elem, text_type):
            elem = Requirement.coerce(elem)
        if replace and elem in self:
            self.remove(elem)
        super(Requirements, self).add(elem)
def test_ccode_Pow():
    assert ccode(x**3) == "pow(x, 3)"
    assert ccode(x**(y**3)) == "pow(x, pow(y, 3))"
    assert ccode(1/(g(x)*3.5)**(x - y**x)/(x**2 + y)) == \
        "pow(3.5*g(x), -x + pow(y, x))/(pow(x, 2) + y)"
    assert ccode(x**-1.0) == '1.0/x'
    assert ccode(x**Rational(2, 3)) == 'pow(x, 2.0L/3.0L)'
    _cond_cfunc = [(lambda base, exp: exp.is_integer, "dpowi"),
                   (lambda base, exp: not exp.is_integer, "pow")]
    assert ccode(x**3, user_functions={'Pow': _cond_cfunc}) == 'dpowi(x, 3)'
    assert ccode(x**3.2, user_functions={'Pow': _cond_cfunc}) == 'pow(x, 3.2)'