anchor.diff:  effects share the same notion of the point at which they are being
   rendered, and create a consistent look:
   
  -code,clojure----------------------------------------------------------------------------------------
  -code,clojure
  +[source,clojure]
  +----
   (afterglow.rhythm/metro-snapshot (:metronome sample-show))
   ; -> #afterglow.rhythm.MetronomeSnapshot{:start 1431727332206, :bpm 120, :bpb 4, :bpp 8,
   ;    :instant 1431727683636, :beat 703, :bar 176, :phrase 22,
   ;    :beat-phase 0.8600000000000136, :bar-phase 0.7150000000000034,
   ;    :phrase-phase 0.9643750000000004}
  -----------------------------------------------------------------------------------------
  +----
   
   Although this captures all of the information, it is not necessarily in
   the format you want it, for example the beat number and bar number are
  
positive.code: The metronome starts counting from the moment it was created, and you
  can ask it for all the counts as a string by calling:
  
  code,clojure--------------------------------------------------------
  code,clojure
  (afterglow.rhythm/metro-marker (:metronome sample-show))
  ; -> "15.1.4"
  --------------------------------------------------------
  
  For that metronome, the current count was phrase 15, bar 1, beat 4. You
  can determine those values as individual numbers as well, but you might
  
negative.code: is being used, and it’s been a long time, since that can drift, unlike
  Pro DJ Link sync:
  
  [source,clojure]
  ----
  (afterglow.rhythm/metro-start (:metronome sample-show) 1)
  ; -> 1431727642086
  ----
  
  ____
  The new metronome start timestamp is returned.
  ____
  
  If the beats are landing in the right place but the notion of the down
  beat (bar start) or phrase start is wrong, you can reset those by
  