int foo(ref x)
a = 5
end
foo( 3 )
-- -- --
s(:expressions,
s(:function, :int,
s(:name, :foo),
s(:parameters,
s(:parameter, :ref, :x)),
s(:assign,
s(:name, :a),
s(:int, 5)))),
s(:call,
s(:arguments,
s(:int, 3))))