code: def test_var_reduction():
      var = lambda x, *args, **kwargs: tile(x.var(*args, **kwargs))
  
      res1 = var(ones((10, 8), chunk_size=3), ddof=2)
      assert res1.shape == ()
      assert res1.op.ddof == 2
  
      res1 = var(ones((10, 8, 8), chunk_size=3), axis=1)
      assert res1.shape == (10, 8)
  
file_path: mars/mars/tensor/reduction/tests/test_reduction.py
imports: import numpy
  import pytest
  from ....core import tile
  from ....core.operand import OperandStage
  from ...datasource import ones, tensor
  from ...merge import TensorConcatenate
  from ..None import all, TensorMean, TensorArgmax, TensorArgmin
label_desc: Use image node_id 6 for calling a global function with example usage: test_var_reduction() without return types