Add a fib example

examples/misc/lastFib.ik

@@ -0,0 +1,30 @@
+
+FibSequence = Sequence with(
+  initialize: method(
+    @index = 0
+    @last1 = 1
+    @last2 = 1
+  ),
+
+  next?: true,
+  next: method(
+    result = case(@index,
+      0, 1,
+      1, 1,
+      else, @last1 + @last2)
+
+    @index++
+    @last1 = @last2
+    @last2 = result
+
+    result
+  )
+)
+
+fib = method("Returns a sequence that generates all the fibonacci numbers",
+  FibSequence mimic
+)
+
+; find the index of the first fibonacci number larger than a thousand
+(fib indexed(from: 1) takeWhile(second < 1000) last first + 1) println
+fib indexed(from: 1) droppedWhile(second < 1000) first first println