code: def test_Mean(value_stream, res_axis_none, res_axis_0, res_axis_1):
      for axis, expected_result in zip(
          [None, 0, 1], [res_axis_none, res_axis_0, res_axis_1]
      ):
          mean = Mean(axis=axis)
          for values in value_stream:
              mean.step(values)
  
          np.testing.assert_almost_equal(mean.get(), expected_result)
  
imports: import numpy
  import pytest
  from gluonts.ev.aggregations import Mean, Sum
  from gluonts.itertools import power_set
label_desc: Use image node_id 2 for calling a global function with example usage: test_Mean(value_stream, res_axis_none, res_axis_0, res_axis_1) without return types