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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 _update_mtime(self):
 """ Updates modif time """

        try:
            self._mtime = os.path.getmtime(self.editor.file.path)
        except OSError:
            # file_path does not exists.
            self._mtime = 0
            self._timer.stop()
        except (TypeError, AttributeError):
            # file path is none, this happen if you use setPlainText instead of
            # openFile. This is perfectly fine, we just do not have anything to
            # watch
            try:
                self._timer.stop()
            except AttributeError:
                pass