docs: def unsubscribe(user_id, from_all=False, campaign_ids=None, on_error=None, on_success=None):
      """ Unsubscribe a user from some or all campaigns.
  
      :param str | number user_id: the id you use to identify a user. this should
      be static for the lifetime of a user.
  
      :param bool from_all True to unsubscribe from all campaigns. Take precedence over
      campaigns IDs if both are given.
  
      :param list of str campaign_ids List of campaign IDs to unsubscribe the user from.
  
      :param func on_error: An optional function to call in the event of an error.
      on_error callback should take 2 parameters: `code` and `error`. `code` will be
      one of outbound.ERROR_XXXXXX. `error` will be the corresponding message.
  
      :param func on_success: An optional function to call if/when the API call succeeds.
      on_success callback takes no parameters.
      """
      __subscription(
          user_id,
          unsubscribe=True,
          all_campaigns=from_all,
          campaign_ids=campaign_ids,
          on_error=on_error,
          on_success=on_success,
      )