(from-pairs [[b 2] [a 1]])
(from-pairs [])
(from-pairs null)
(from-pairs [[a 1] [b 2] [a 3]])
(from-pairs [[a 1] [a null] [b false]])
(from-pairs [["" 0] ["/a" 1] [a/b 2]])
(from-pairs [[nested {a 1}] [items [1 2]]])
(from-pairs
  (pairs
    {<!z>
     a null
     nested {b 2}}))
(pairs (from-pairs [[z 1] [a 2] [z 3]]))