code: def _bind_parse_additional_data(self, key, multiline=False):
          
  
          def _set_additional_data_bound(self, data):
              """Concrete method for setting additional data
              :param self:
              :type self: OldHEPData
              """
              # if it's multiline, parse it
              if multiline:
                  data = self._read_multiline(data)
  
              if key not in self.additional_data:
                  self.additional_data[key] = []
              self.additional_data[key].append(data)
  
          # method must be bound, so we use __get__
          return _set_additional_data_bound.__get__(self)
docs: Returns parsing function which will parse data as text, and add it to the table additional data dictionary
          with the provided key
  
          :param key: dictionary key under which parsed data will be added to table.metadata
          :type key: str
          :param multiline: if True this attribute will be treated as multiline
          :type multiline: bool
          :return: function with bound key and multiline attributes
          :rtype: Function