code: def test_zero_fold(self):
      a, b = Tensor.randn(1).realize(), Tensor.randn(1).realize()
      r = Tensor.stack([a, b])
  
      k = Linearizer(r.lazydata.schedule()[-1].ast)
      k.upcast()
      k.linearize()
      num_ops = len([uop for uop in k.uops if uop.uop == UOps.ALU])
      assert num_ops == 0, "more alu uops than needed"
  
imports: import numpy
  import unittest, os
  from tinygrad.codegen.kernel import Opt, OptOps, tensor_cores
  from tinygrad.codegen.linearizer import Linearizer, UOp, UOps, expand_node
  from tinygrad.device import Compiled, Device, Buffer
  from tinygrad.ops import BufferOps, MemBuffer, ConstBuffer, LazyOp, LoadOps, TernaryOps
  from tinygrad.shape.shapetracker import ShapeTracker
  from tinygrad.shape.view import View
  from tinygrad.shape.symbolic import MulNode, SumNode, Variable, NumNode, Node, create_rednode
  from tinygrad.tensor import Tensor
  from tinygrad.jit import CacheCollector
  from tinygrad.realize import run_schedule
  from tinygrad.helpers import prod
  from tinygrad.dtype import dtypes
label_desc: Use image node_id 4 for calling the TestLinearizer obj's underlying member method code with example usage: obj.test_zero_fold() without return types