true if they are a full overlap

      :return: is full overlap
      :rtype: bool

def is_full_overlap(self1):
      """true if they are a full overlap

      :return: is full overlap
      :rtype: bool
      """
      if len(self1.overs) == 0: return False
      if len(self1.dif1) > 0:
        if max(self1.dif1) != 1 or max(self1.dif2) != 1: return False
      if self1.start1 and self1.end1 and self1.start2 and self1.end2:
        return True
      return False