docs: def get_hdrs_len(self):
          # type: () -> int
          """ get_hdrs_len computes the length of the hdrs field
  
          To do this computation, the length of the padlen field, the priority
          information fields and the actual padding is subtracted to the string
          that was provided to the pre_dissect fun of the pkt parameter.
          @return int: the length of the hdrs field
          @raise AssertionError
          """
  
          padding_len = self.getfieldval('padlen')
          fld, fval = self.getfield_and_val('padlen')
          padding_len_len = fld.i2len(self, fval)
          bit_cnt = self.get_field('exclusive').size
          bit_cnt += self.get_field('stream_dependency').size
          fld, fval = self.getfield_and_val('weight')
          weight_len = fld.i2len(self, fval)
          ret = int(self.s_len -
                    padding_len_len -
                    padding_len -
                    (bit_cnt / 8) -
                    weight_len
                    )
          assert(ret >= 0)
          return ret