Section 20J. Any person arrested in this commonwealth charged with having committed any crime in another state or with having been convicted in another state and having escaped from confinement or having broken the terms of his bail, probation or parole, may waive the issuance and service of the warrant provided for in sections sixteen and seventeen and all other procedure incidental to interstate rendition proceedings, by executing or subscribing in the presence of any court or justice of this commonwealth authorized to issue warrants in criminal cases a writing which states that he consents to return to the demanding state; provided, that if such waiver shall be executed or subscribed by such person it shall be the duty of such court or justice to inform such person of his rights to the issuance and service of a warrant in interstate rendition and to obtain a writ of habeas corpus as provided in section nineteen. If and when such consent has been duly executed it shall forthwith be forwarded to the office of the governor and filed therein. Such court or justice shall direct the officer having such person in custody to deliver forthwith such person to the duly accredited agent of the demanding state, and shall deliver or cause to be delivered to such agent a copy of such consent; provided, that nothing in this section shall be deemed to limit the right of the accused person to return voluntarily and without formality to the demanding state, nor shall the foregoing waiver procedure be deemed to be an exclusive procedure or to limit the powers, rights or duties of the officers of the demanding state or of this commonwealth.