def _sort_tp_file(
            self,
            taskpaperPath):
        """*sort individual taskpaper documents*

        **Key Arguments:**
            - ``taskpaperPath`` -- path to a taskpaper file

        **Return:**
            - None
        """
        self.log.info('starting the ``_sort_tp_file`` method')

        # OPEN TASKPAPER FILE

        self.log.info("sorting taskpaper file %(taskpaperPath)s" % locals())
        doc = document(taskpaperPath)
        doc.tidy()
        doc.sort_tasks(self.settings["workflowTags"])
        doc.sort_projects(self.settings["workflowTags"])
        doc.save()

        self.log.info('completed the ``_sort_tp_file`` method')
        return None