code: def test_multi_block_append(
      ant, sphere, uniform, airplane, rectilinear
  ):
      """This puts all of the example data objects into a a MultiBlock container"""
      multi = MultiBlock()
      # Add and test examples
      datasets = (ant, sphere, uniform, airplane, rectilinear)
      for i, dataset in enumerate(datasets):
          multi.append(dataset)
          assert multi.n_blocks == i + 1
          assert isinstance(multi[i], type(dataset))
      assert multi.bounds is not None
      # Now overwrite a block
      multi[4] = pv.Sphere()
      assert isinstance(multi[4], PolyData)
      multi[4] = vtk.vtkUnstructuredGrid()
      assert isinstance(multi[4], pv.UnstructuredGrid)
  
      with pytest.raises(
          ValueError, match="Cannot nest a composite dataset in itself."
      ):
          multi.append(multi)
  
imports: import pathlib
  import platform
  import weakref
  import numpy
  import pytest
  import vtk
  import pyvista
  from pyvista import ImageData, MultiBlock, PolyData, RectilinearGrid, StructuredGrid, examples
label_desc: Use image node_id 6 for calling a global function with example usage: test_multi_block_append(ant, sphere, uniform, airplane, rectilinear) without return types