class Pifi
  ofthen(3 , var)

  int self.ofthen(int n , ref m)
    n = n + m.index
    return n
  end
end
-- -- --
s(:expressions,
  s(:class, :Pifi,
    s(:derives, nil),
    s(:expressions,
      s(:call,
        s(:name, :ofthen),
        s(:arguments,
          s(:int, 3),
          s(:name, :var))),
      s(:function, :int,
        s(:name, :ofthen),
        s(:parameters,
          s(:parameter, :int, :n),
          s(:parameter, :ref, :m)),
        s(:expressions,
          s(:assign,
            s(:name, :n),
            s(:operator, "+",
              s(:name, :n),
              s(:field_access,
                s(:receiver,
                  s(:name, :m)),
                s(:field,
                  s(:name, :index))))),
          s(:return,
            s(:name, :n))),
        s(:receiver, :self)))))