def METHOD_NAME(self):
    """
    Returns the one of the group, which index the one of this algebra,
    as per :meth:`AlgebrasWithBasis.ParentMethods.one_basis`.
    EXAMPLES::
        sage: A = HopfAlgebrasWithBasis(QQ).example()
        sage: A.one_basis()
        ()
        sage: A.one()
        B[()]
    """
    return self._group.one()