def update_config! attr, val
      Execute.task_popen3(*override_a, "config #{attr} #{val}") do |i, o, e, t|
        return t.value
      end
    end
def update_config! attr, val
      Execute.task_popen3(*override_a, "config #{attr} #{val}") do |i, o, e, t|
        return t.value
      end
    end
Update a configuration variable in the .taskrc

 @param attr [String]
 @param val [String]
 @return [Process::Status] the exit status of the thread
 @api public