code: def test_multi_block_keys(rectilinear, airplane):
      data = {"grid": rectilinear, "poly": airplane}
      multi = MultiBlock(data)
      assert len(multi.keys()) == 2
      assert "grid" in multi.keys()
      assert "poly" in multi.keys()
  
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 4 for calling a global function with example usage: test_multi_block_keys(rectilinear, airplane) without return types