anchor.diff:  "Person","Allan Williams"
   "Group","The Quarrymen"
   "Album","Please Please Me"
  -"Album","With The Beatles"
  +"Album","With the Beatles"
   "Album","Introducing... The Beatles"
   "Album","Meet the Beatles!"
   "Album","The Beatles' Second Album"
  
positive.code: "Song","Happiness Is a Warm Gun"
  "Song","Martha My Dear"
  "Song","I'm So Tired"
  "Song","Blackbird (song)"
  "Song","Piggies"
  "Song","Rocky Raccoon"
  "Song","Don't Pass Me By"
  
negative.code: "Song","Free as a Bird"
  "Song","I Saw Her Standing There"
  "Song","This Boy"
  "Song","Real Love (The Beatles song)"
  "Song","Misery (Beatles song)"
  "Song","Anna (Go to Him)"
  "Song","Chains (Cookies song)"
  "Song","Boys (The Shirelles song)"
  "Song","Ask Me Why"
  "Song","Baby It's You"
  "Song","Do You Want to Know a Secret"
  