code: def parse(self):
          
          for line in self.lines:
              # Parse the line
              field_defs = self.parse_line(line)
              fields = []
  
              # Convert field parameters into Field objects
              for (kind, options) in field_defs:
                  logger.debug("Creating field %s(%r)", kind, options)
                  fields.append(self.field_registry.create(kind, **options))
  
              # Add the list of Field objects to the 'fields per line'.
              self.line_fields.append(fields)
  
              # Pre-fill the list of widgets
              for field in fields:
                  self.widgets[field] = None
docs: Parse the lines, and fill self.line_fields accordingly.