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http://rosettacode.org/wiki/Anonymous_recursion
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⟦import java.util.function.UnaryOperator;⟧

■ AnonymousRecursion
  § static
    ▶ main
    • args⦂ String[]
      if 0 > Integer.valueOf args[0]
         System.out.println "negative argument"
      else
         System.out.println *UnaryOperator⟨Integer⟩° ■
           ▶ apply⦂ Integer
           • n⦂ Integer
             ⏎ n ≤ 1 ? n ! (apply n - 1) + (apply n - 2)
         °.apply Integer.valueOf args[0]