@classmethod
def between(cls, a, b, closed=True):
    """Returns an interval between two values

        Returns an interval between values a and b.  If closed is True,
        then the endpoints are included.  Otherwise, the endpoints are
        excluded.

        >>> print Interval.between(2, 4)
        [2..4]
        >>> print Interval.between(2, 4, False)
        (2..4)
        """
    return cls(a, b, closed=closed)
