code: def test_var_vals_mask(self):
      x = Variable("x", 1, 100).bind(3)
      view = View.create(
          shape=(3, 4), strides=(4, 1), offset=0, mask=((0, x), (0, 4))
      )
      st = ShapeTracker(views=(view,))
      assert st.var_vals == {Variable("x", 1, 100): 3}
  
imports: import unittest
  from tinygrad.shape.shapetracker import ShapeTracker, View
  from tinygrad.shape.symbolic import Variable, NumNode
  from tinygrad.tensor import Tensor
label_desc: Use image node_id 4 for calling the TestSymbolicVarVals obj's underlying member method code with example usage: obj.test_var_vals_mask() without return types