code: def test_highlight_null_subset(styler):
      # GH 31345
      result = (
          styler.highlight_null(color="red", subset=["A"])
          .highlight_null(color="green", subset=["B"])
          ._compute()
          .ctx
      )
      expected = {
          (1, 0): [("background-color", "red")],
          (1, 1): [("background-color", "green")],
      }
      assert result == expected
  
file_path: pandas/pandas/tests/io/formats/style/test_highlight.py
imports: import numpy
  import pytest
  from pandas import NA, DataFrame, IndexSlice
  from pandas.io.formats.style import Styler
label_desc: Use image node_id 4 for calling a global function with example usage: test_highlight_null_subset(styler) without return types