nodes: 0, module; 1, function_definition; 2, function_name:label_values; 3, parameters; 4, block; 5, identifier:self; 6, expression_statement; 7, expression_statement; 8, return_statement; 9, comment:"""
          Return a list of all occuring label values.
  
          Returns:
              list: Lexicographically sorted list (str) of label values.
  
          Example:
              >>> ll = LabelList(labels=[
              >>>     Label('a', 3.2, 4.5),
              >>>     Label('b', 5.1, 8.9),
              >>>     Label('c', 7.2, 10.5),
              >>>     Label('d', 10.5, 14),
              >>>     Label('d', 15, 18)
              >>> ])
              >>> ll.label_values()
              ['a', 'b', 'c', 'd']
          """; 10, assignment; 11, call; 12, identifier:all_labels; 13, call; 14, identifier:sorted; 15, argument_list; 16, identifier:set; 17, argument_list; 18, identifier:all_labels; 19, list_comprehension; 20, attribute; 21, for_in_clause; 22, identifier:l; 23, identifier:value; 24, identifier:l; 25, identifier:self
code: def label_values(self):
          """
          Return a list of all occuring label values.
  
          Returns:
              list: Lexicographically sorted list (str) of label values.
  
          Example:
              >>> ll = LabelList(labels=[
              >>>     Label('a', 3.2, 4.5),
              >>>     Label('b', 5.1, 8.9),
              >>>     Label('c', 7.2, 10.5),
              >>>     Label('d', 10.5, 14),
              >>>     Label('d', 15, 18)
              >>> ])
              >>> ll.label_values()
              ['a', 'b', 'c', 'd']
          """
  
          all_labels = set([l.value for l in self])
          return sorted(all_labels)