code: def targets_for_class(self, target, classname):
      
      targets_with_class = set()
      for target in target.closure():
        for one_class in self._target_classes(target):
          if classname in one_class:
            targets_with_class.add(target)
            break
  
      return targets_with_class
docs: Search which targets from `target`'s transitive dependencies contain `classname`.