code: def test_ref():
      i = relay.Var("i")
      iv = relay.Var("iv")
      u = relay.Var("u")
      uv = relay.Var("uv")
      body = relay.add(iv, uv)
      body = relay.Let(uv, relay.RefRead(i), body)
      body = relay.Let(u, relay.RefWrite(i, relay.const(2)), body)
      body = relay.Let(iv, relay.RefRead(i), body)
      body = relay.Let(i, relay.RefCreate(relay.const(1)), body)
      check_eval(body, 3)
      opt_body = run_opt_pass(body, transform.ToANormalForm())
      check_eval(opt_body, 3)
  
imports: import pytest
  import sys
  import numpy
  import tvm
  import tvm.testing
  from tvm import te
  from tvm import relay
  from tvm.relay.analysis import detect_feature
  from tvm.relay import op, create_executor, transform
  from tvm.relay.prelude import Prelude
  from tvm.relay.testing import count
  from tvm.relay.analysis import Feature
label_desc: Use image node_id 8 for calling a global function with example usage: test_ref() without return types