(a) In addition to the methods of termination prescribed by Sections 411 through 414, a trust terminates to the extent the trust is revoked or expires pursuant to the trust instrument, no purpose of the trust remains to be achieved, or the purposes of the trust have become unlawful, contrary to public policy, or impossible to achieve.
     (b) A proceeding to approve or disapprove a proposed modification or termination under Sections 411 through 416, or trust combination or division under Section 417, may be commenced by a trustee or beneficiary or by the Attorney General for a trust with a charitable interest. The settlor of a charitable trust may maintain a proceeding to modify the trust under Section 413.