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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 sort_func(self, key):
 """Specify order for attributes."""

        if key == self._KEYS.TIME:
            return 'aaa'
        if key == self._KEYS.MODEL:
            return 'zzy'
        if key == self._KEYS.SOURCE:
            return 'zzz'
        return key