code: def is_non_zero_before_non_zero(self, other):
          
          return self.is_adjacent_before(other) and (not self.has_zero_length) and (not other.has_zero_length)
docs: Return ``True`` if this time interval ends
          when the given other time interval begins,
          and both have non zero length.
  
          :param other: the other interval
          :type  other: :class:`~aeneas.exacttiming.TimeInterval`
          :raises TypeError: if ``other`` is not an instance of ``TimeInterval``
          :rtype: bool