code: def __label_cmp(self, other):
          
          if other is None:
              return -1
  
          label_name = strip_accents(self.name).lower()
          other_name = strip_accents(other.name).lower()
          if label_name < other_name:
              return -1
          elif label_name == other_name:
              return 0
          else:
              return 1
  
          if self.get_color_str() < other.get_color_str():
              return -1
          elif self.get_color_str() == other.get_color_str():
              return 0
          else:
              return 1
docs: Comparaison function. Can be used to sort labels alphabetically.