Data update

Task/Fibonacci-sequence/Rebol/fibonacci-sequence.rebol

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+Rebol [
+    title: "Rosetta code: Fibonacci sequence"
+    file:  %Fibonacci_sequence.r3
+    url:   https://rosettacode.org/wiki/Fibonacci_sequence
+]
+
+fibonacci: function/with [
+    {Return the Nth Fibonacci number using iterative state advancement.
+    Uses a shared block to swap fn and fn-1 in a single expression.}
+    number [integer!]  "which Fibonacci number to compute (0-indexed)"
+][
+    fn-1: 0                                    ;; F(0)
+    fn:   1                                    ;; F(1)
+    loop number advance-fibonacci
+][
+    fn: fn-1: 0
+    advance-fibonacci: [ fn: fn-1 + fn-1: fn ] ;; simultaneously: new fn = old fn + old fn-1
+]
+
+probe collect [repeat i 18 [keep fibonacci i]]