Miller bought a ski lift ticket at a resort in New Hampshire. He was injured when he hit some snow making equipment that was buried under snow. He sued for negligence. The resort claimed he assumed the risk because he agreed to a liability waiver that was printed on the lift ticket. He contended he did not sign the agreement, so it was not valid. Is that right? [Miller v. Sunapee Difference, 918 F.3d 172, 1st Cir. (2019)]