anchor.diff:  
   [source,clojure]
   ----
  -(afterglow.effects.fun/sparkle (show/all-fixtures))
  +(show/add-effect! :sparkle
  +  (afterglow.effects.fun/sparkle (show/all-fixtures)))
   ----
   
   ==== Strobe
  
positive.code: 
  [source,clojure]
  ----
  (afterglow.effects.fun/wipe-right-color-cycle-chase (show/all-fixtures))
  ----
  
  ==== Sparkle
  
negative.code: 
  [source,clojure]
  ----
  (show/add-effect! :color
    (afterglow.effects.fun/metronome-effect (show/all-fixtures)))
  ----
  
  Creates an effect which flashes the heads of the supplied fixtures one
  