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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 _is_modified(self, filepath):
 """ Returns True if the file has been modified since last seen. Will return False if the file has not been seen before. """

        if self._is_new(filepath):
            return False
        mtime = self._get_modified_time(filepath)
        return self._watched_files[filepath] < mtime