code: def object_path(self, key):
      '''return the object path for `key`.'''
      return os.path.join(self.root_path, self.relative_object_path(key)f object_path(self, key):
      '''return the object path for `key`.'''
      return os.path.join(self.root_path, self.relative_object_path(key))
docs: return the object path for `key`.