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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _modifyItemTag(self, item_id, action, tag):
 """ wrapper around actual HTTP POST string for modify tags """

        return self.httpPost(ReaderUrl.EDIT_TAG_URL,
                             {'i': item_id, action: tag, 'ac': 'edit-tags'})