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