code: def get_write_fields(self):
          
  
          # Record specification fields
          write_fields = self.get_write_subset('record')
  
          # Segment specification fields are all mandatory
          write_fields = write_fields + ['seg_name', 'seg_len']
  
          # Comments
          if self.comments !=None:
              write_fields.append('comments')
          return write_fields
docs: Get the list of fields used to write the multi-segment header.
          Returns the default required fields, the user defined fields,
          and their dependencies.