code: def change_message_visibility(self, queue, receipt_handle,
                                    visibility_timeout, callback=None):
          
          params = {'ReceiptHandle' : receipt_handle,
                    'VisibilityTimeout' : visibility_timeout}
          return self.get_status('ChangeMessageVisibility', params, queue.id, callback=callback)
docs: Extends the read lock timeout for the specified message from
          the specified queue to the specified value.
  
          :type queue: A :class:`boto.sqs.queue.Queue` object
          :param queue: The Queue from which messages are read.
          
          :type receipt_handle: str
          :param queue: The receipt handle associated with the message whose
                        visibility timeout will be changed.
          
          :type visibility_timeout: int
          :param visibility_timeout: The new value of the message's visibility
                                     timeout in seconds.