code: def composite_mapper(multiblock_poly):
      pl = pv.Plotter()
      actor, mapper = pl.add_composite(multiblock_poly)
      return mapper
  
imports: import pytest
  from vtkmodules.vtkCommonCore import vtkLookupTable
  import pyvista
  from pyvista.plotting.composite_mapper import BlockAttributes, CompositePolyDataMapper
label_desc: Use image node_id 1 for calling a global function with example usage: composite_mapper(multiblock_poly) and returns: mapper