add list splats

(var a [ 1 2 ]
  b [ 4 5 ])

[ 0 ...a 3 ...b 6 7 ] ;=> [ 0 1 2 3 4 5 6 ]


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my plan is to add this to lambda as well, so we'll be able to
(myfunc a b ...rest-of-args)

which would be the same as
(apply myfunc [ a b ...rest-of-args ])