anchor.diff:  ====
   
   ====
  -`union` - TBD --> to get working
  -"Merge multiple time-ordered sequences of disjoint intervals into a
  -  single sequence of time-ordered disjoint intervals."
  -[source.code,clojure]
  -----
  -(t/union (t/new-interval (t/instant "2000-01-01T00:00") (t/instant "2000-01-02T00:00"))
  -	 (t/new-interval (t/instant "2000-01-02T00:00") (t/instant "2000-02-02T00:00")))
  +`union` - Join two time-ordered sequences together into one ordered sequence
  +[source.code,clojure]
  +----
  +(t/union [(t/today)] [(t/yesterday) (t/tomorrow)])
   ----
   ====
   
  
positive.code: ====
  
  ====
  `compare-and-set!` - TBD (Atomic clocks)
  [source.code,clojure]
  ----
  
  ----
  ====
  
  ====
  `complement` - Give the inverse intervals. - TBD : better description.
  [source.code,clojure]
  ----
  (t/complement [(t/instant "2010-01-01T00:00")
  
negative.code: ====
  
  ====
  `ordered-disjoint-intervals?` - Are the given intervals time-ordered and disjointed?
  [source.code,clojure]
  ----
  (t/ordered-disjoint-intervals? [(t/new-interval (t/instant "2000-01-01T00:00")
  