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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 _format_lon(self, lon):
        ''' Returned a formated longitude format for the file '''
        if self.ppd in [4, 16, 64, 128]:
            return None
        else:
            return map(lambda x: "{0:0>3}".format(int(x)), self._map_center('long', lon))