code: def test_graph_category_item_remove_none():
      item = GraphCategory()
      expected = {}
      assert_equal(expected, remove_key_with_none_value(item.opts))
  
file_path: pyecharts/test/test_chart_options.py
imports: from nose.tools import assert_equal
  from pyecharts.commons.utils import remove_key_with_none_value
  from pyecharts.options.charts_options import BarBackgroundStyleOpts, GlobeLayersOpts, GraphCategory, ThemeRiverItem, TimelineCheckPointerStyle, TimelineControlStyle, TreeItem, TreeMapItemStyleOpts, GraphicImageStyleOpts, GraphicTextStyleOpts, GeoRegionsOpts
label_desc: Use image node_id 7 for calling a global function with example usage: test_graph_category_item_remove_none() without return types