code: def append_data(self, len_tag, val_tag, data, header=False):
          
  
          self.append_pair(len_tag, len(data), header=header)
          self.append_pair(val_tag, data, header=header)
          return
docs: Append raw data, possibly including a embedded SOH.
  
          :param len_tag: Tag number for length field.
          :param val_tag: Tag number for value field.
          :param data: Raw data byte string.
          :param header: Append to header if True; default to body.
  
          Appends two pairs: a length pair, followed by a data pair,
          containing the raw data supplied.  Example fields that should
          use this method include: 95/96, 212/213, 354/355, etc.