How to create a normalization rule and process which will change a string of part of the URL in the 856 subfield u

Question: Hi Yoel,I’m having trouble creating a norm rule to alter a small section of a url in an 856 field. HeinOnline has changed part of their url from https://www.heinonline.org to https://access.heinonline.com For example: $$z HeinOnline U.S.