def METHOD_NAME(verbose=0):
  if (verbose): print('Checking flex->ref conversions')
  s = rt.make_shared()
  assert rt.use_const_ref(s) == 6
  rt.modify_ref(s)
  assert tuple(s) == (6,2,4)
  assert rt.use_const_ref(None) == 0
  rt.modify_ref(None)
  if (verbose): print('OK')