"It turned out to be a great laugh at the same time as challenging because you suddenly realize you've got to compress a musical interpretation of an expression into less than five seconds," said McCartney in a prepared statement.

"It was like doing a huge crossword puzzle and coming up with all these solutions. And at the same time it was musical so it was great practice for me in the studio."

"I wanted it to sound sort of electronic," he continues "so I wanted the signature to sound electronic rather than acoustic guitar, for instance. So I got the overall signature on the Moog in order to give it a modern flavor."