There shall be a provision that the insurer will furnish to the policyholder such forms as are usually furnished by it for filing proof of loss. If such forms are not furnished before the expiration of 15 days after the insurer received notice of any claim under the policy, the person making such claim shall be deemed to have complied with the requirements of the policy as to proof of loss upon submitting within the time fixed in the policy for filing proof of loss, written proof covering the occurrence, character and extent of the loss for which claim is made. [PL 1969, c. 132, §1 (NEW).]