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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 _watch_file(self, filepath, trigger_event=True):
 """Adds the file's modified time into its internal watchlist."""

        is_new = filepath not in self._watched_files
        if trigger_event:
            if is_new:
                self.trigger_created(filepath)
            else:
                self.trigger_modified(filepath)
        try:
            self._watched_files[filepath] = self._get_modified_time(filepath)
        except OSError:
            return