def __init__(self, package, version):
        """Construct a new requirement.

        :param package: the package name.
        :param version: a semver compatible version specification.
        """
        self.package = package
        self.version = version
        if self.version and not re.match(r"[<=>~]", version[:2]):
            self.version = "=={}".format(self.version)
def test_reverse_iso8601_datetime():
    dates = [
        ("2011-01-01T00:00:00+00:00", datetime(2011, 1, 1, tzinfo=pytz.utc)),
        ("2011-01-01T23:59:59+00:00", datetime(2011, 1, 1, 23, 59, 59, tzinfo=pytz.utc)),
        ("2011-01-01T23:59:59.001000+00:00", datetime(2011, 1, 1, 23, 59, 59, 1000, tzinfo=pytz.utc)),
        ("2011-01-01T23:59:59+02:00", datetime(2011, 1, 1, 21, 59, 59, tzinfo=pytz.utc))
    ]

    for date_string, expected in dates:
        yield assert_equal, inputs.datetime_from_iso8601(date_string), expected