actor Main
  new create(env: Env) =>
    let fox = recover Fox(env) end
    let wolf = Wolf(env, consume fox)
    wolf()
    wolf()

class Wolf
  let _env: Env
  let fox: Fox ref

  new create(env: Env, fox': Fox iso) =>
    _env = env
    fox = consume fox'

  //  v-- inserting a "ref" here fixes the issue
  fun ref apply() =>
    _env.out.print("Wolf: I'm in a ref function! 🐺")
    fox()

class Fox
  let _env: Env
  var _x: U32 = 0

  new create(env: Env) =>
    _env = env

  fun ref apply() =>
    _x = _x + 1
    _env.out.print("Fox: I'm in a ref function, and look at my number: " + _x.string() + " 🦊")