Input (grade 5): Lennon changed it to Pam when he saw the opportunity to ease the segue into the song "Polythene Pam", which follows "Mean Mr. Mustard" on the album.
Output (grade 4): Lennon changed it to Pam when he saw the ochance to ease the segue into the song "Polythene Pam", which is after "Mean Mr. Mustard" on the album.