// replace calls of returned functions by .apply for clarity
  // these are our calls to g
  foldLeftViaFoldRight(List(1,2), 0)(f)

  foldRight(List(1,2), b => b)((a,g) => b => g(f(b, a)))(0)
  (b1 => foldRight(List(2), b => b)((a,g) => b => g(f(b, a))).apply(f(b1, 1)))(0) // (1)

  // look at inner fold right separately:
  foldRight(List(2), b => b)((a,g) => b => g(f(b, a)))
  b2 => foldRight(Nil, b => b)((a,g) => b => g(f(b, a))).apply(f(b2, 2))
  b2 => (b => b).apply(f(b2, 2)) // we reach zero element, identity
  b2 => f(b2, 2))

  // insert into (1)
  (b1 => (b2 => f(b2, 2)).apply(f(b1, 1)))(0)
  (b2 => f(b2, 2)).apply(f(0, 1))) // apply the function from foldRight to zero value
  f(f(0, 1), 2))