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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 bbox(self, outname=None, format='ESRI Shapefile', overwrite=True):
 """ create a bounding box from the extent of the Vector object Parameters outname: str or None the name of the vector file to be written; if None, a Vector object is returned format: str the name of the file format to write overwrite: bool overwrite an already existing file? Returns ------- Vector or None if outname is None, the bounding box Vector object """

        if outname is None:
            return bbox(self.extent, self.srs)
        else:
            bbox(self.extent, self.srs, outname=outname, format=format, overwrite=overwrite)