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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):
        ''' Format longitude to fit the image name '''

        lonf = self._map_center('long', lon)
        st = str(lonf).split('.')
        loncenter = ''.join(("{0:0>3}".format(st[0]), st[1]))
        return loncenter