'Compare two Epoch\'s.
= INPUT VARIABLES
- rhs    The Epoch to compare against.
= RETURN VALUE
- Returns -1 if self < rhs, 0 if self == rhs, +1 if self > rhs.'

def __cmp__(self, rhs):

    t = self
    if (self._frame != rhs._frame):
        t = self.convert(rhs._frame)
    if (t._jd != rhs._jd):
        return cmp(t._jd, rhs._jd)
    return cmp(t._seconds, rhs._seconds)
