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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 __getFileObj(self, f):

 """Checks to see if the requested shapefile file object is
 available. If not a ShapefileException is raised."""

        if not f:
            raise ShapefileException("Shapefile Reader requires a shapefile or file-like object.")
        if self.shp and self.shpLength is None:
            self.load()
        if self.dbf and len(self.fields) == 0:
            self.load()
        return f