code: def get_collection(self, lang=None, task=None):
      
      if lang: id = "{}{}".format(Downloader.LANG_PREFIX, lang)
      elif task: id = "{}{}".format(Downloader.TASK_PREFIX, task)
      else: raise ValueError("You should pass either the task or the lang")
      try:
        return self.info(id)
      except ValueError as e:
        if lang: raise LanguageNotSupported("Language {} is not supported".format(id))
        if task: raise TaskNotSupported("Task {} is not supported".format(id))
docs: Return the collection that represents a specific language or task.
  
      Args:
        lang (string): Language code.
        task (string): Task name.