code: def __validateExperimentControl(self, control):
      
      # Validate task list
      taskList = control.get('tasks', None)
      if taskList is not None:
        taskLabelsList = []
  
        for task in taskList:
          validateOpfJsonValue(task, "opfTaskSchema.json")
          validateOpfJsonValue(task['taskControl'], "opfTaskControlSchema.json")
  
          taskLabel = task['taskLabel']
  
          assert isinstance(taskLabel, types.StringTypes), \
                 "taskLabel type: %r" % type(taskLabel)
          assert len(taskLabel) > 0, "empty string taskLabel not is allowed"
  
          taskLabelsList.append(taskLabel.lower())
  
        taskLabelDuplicates = filter(lambda x: taskLabelsList.count(x) > 1,
                                     taskLabelsList)
        assert len(taskLabelDuplicates) == 0, \
               "Duplcate task labels are not allowed: %s" % taskLabelDuplicates
  
      return
docs: Validates control dictionary for the experiment context