prelude: |
  hash = {a: 1}
  arr = [hash]
  arr2 = [1]
  class Object
    def a(x) end
    if ENV['R2']
      ruby2_keywords def foo(*args) bar(*args) end
    else
      def foo(*args, **kw) bar(*args, **kw) end
    end
    def bar(*args) end
  end

  if ENV['R2']
    b = proc do
      300.times{a(*arr)}
      foo(*arr)
    end
  else
    b = proc do
      300.times{a(*arr)}
      foo(*arr, **{})
    end
  end
  c = proc do
    300.times{a(*arr)}
    foo(*arr2)
  end
benchmark:
  worst_case: "a(*arr)"
  one_per_3hundred_hash: "b.call"
  one_per_3hundred_nonhash: "c.call"