code: def test_create_zmap() -> None:
      x_values = np.arange(10)
      y_values = np.arange(10)
      z_values = list(np.random.rand(10))
  
      # we are testing for exact placement of z_values
      # so also passing x_values and y_values as xi and yi
      zmap = _create_zmap(
          x_values.tolist(),
          y_values.tolist(),
          z_values,
          x_values,
          y_values,
      )
  
      assert len(zmap) == len(z_values)
      for coord, value in zmap.items():
          # test if value under coordinate
          # still refers to original trial value
          xidx = coord[0]
          yidx = coord[1]
          assert xidx == yidx
          assert z_values[xidx] == value
  
imports: import numpy
  from optuna.visualization.matplotlib._contour import _create_zmap
  from optuna.visualization.matplotlib._contour import _interpolate_zmap
label_desc: Use image node_id 1 for calling a global function with example usage: test_create_zmap() without return types