templates nthFibonacci
  { N: ($)"1", n0: 0"1", n1: 1"1" } -> #
  when <{ N: <=0"1"> }> do
    $.n0 !
  when <{ N: <1"1"..>}> do
    { N: $.N - 1"1", n0: $.n1, n1: $.n0 + $.n1} -> #
  otherwise
    { N: $.N + 1"1", n1: $.n0, n0: $.n1 - $.n0} -> #
end nthFibonacci

8 -> nthFibonacci -> '$;
' -> !OUT::write
-5 -> nthFibonacci -> '$;
' -> !OUT::write
-6 -> nthFibonacci -> '$;
' -> !OUT::write