docs: 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