return the storer object for a key, raise if not in the file

def get_storer(self, key):
        """ return the storer object for a key, raise if not in the file """
        group = self.get_node(key)
        if group is None:
            raise KeyError('No object named {key} in the file'.format(key=key))

        s = self._create_storer(group)
        s.infer_axes()
        return s