code: def get_task_cls(cls, name):
          
          task_cls = cls._get_reg().get(name)
          if not task_cls:
              raise TaskClassNotFoundException(cls._missing_task_msg(name))
  
          if task_cls == cls.AMBIGUOUS_CLASS:
              raise TaskClassAmbigiousException('Task %r is ambiguous' % name)
          return task_cls
docs: Returns an unambiguous class or raises an exception.