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_urls():
    urls = [
        'http://www.djangoproject.com/',
        'http://localhost/',
        'http://example.com/',
        'http://www.example.com/',
        'http://www.example.com:8000/test',
        'http://valid-with-hyphens.com/',
        'http://subdomain.example.com/',
        'http://200.8.9.10/',
        'http://200.8.9.10:8000/test',
        'http://valid-----hyphens.com/',
        'http://example.com?something=value',
        'http://example.com/index.php?something=value&another=value2',
        'http://foo:bar@example.com',
        'http://foo:@example.com',
        'http://foo:@2001:db8:85a3::8a2e:370:7334',
        'http://foo2:qd1%r@example.com',
    ]

    for value in urls:
        yield assert_equal, inputs.url(value), value