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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 relative_path(self, filepath, basepath=None):
 """ Convert the filepath path to a relative path against basepath. By default basepath is self.basedir. """

        if basepath is None:
            basepath = self.basedir
        if not basepath:
            return filepath
        if filepath.startswith(basepath):
            rel = filepath[len(basepath):]
        if rel and rel[0] == os.sep:
            rel = rel[1:]
        return rel