code: def test_lookup_table(composite_mapper):
      isinstance(composite_mapper.lookup_table, vtkLookupTable)
  
      table = vtkLookupTable()
      composite_mapper.lookup_table = table
      assert composite_mapper.lookup_table is table
  
imports: import pytest
  from vtkmodules.vtkCommonCore import vtkLookupTable
  import pyvista
  from pyvista.plotting.composite_mapper import BlockAttributes, CompositePolyDataMapper
label_desc: Use image node_id 7 for calling a global function with example usage: test_lookup_table(composite_mapper) without return types