Add all the A tasks

Task/Anonymous-recursion/Ruby/anonymous-recursion-6.rb

@@ -0,0 +1,20 @@
+require 'continuation' unless defined? Continuation
+
+module Kernel
+  module_function
+
+  def recur(*args, &block)
+    cont = catch(:recur) { return block[*args] }
+    cont[block]
+  end
+
+  def recurse(*args)
+    block = callcc { |cont| throw(:recur, cont) }
+    block[*args]
+  end
+end
+
+def fib(n)
+  raise RangeError, "fib of negative" if n < 0
+  recur(n) { |m| m < 2 ? m : (recurse m - 1) + (recurse m - 2) }
+end