Nolan wrote the song "Tumbling Tumbleweeds" and, in an agreement with Sam Fox Publishing Company, transferred all rights to the song to the company. In return, Nolan was to receive royalties according to terms laid out in the agreement. Sam Fox later assigned all rights and interests in "TumblingTumbleweeds" to Williamson Music, Inc. Was it necessary for Sam Fox to obtain Nolan's consent before making the assignment to Williamson? Explain.