code: def np_mean_square(input, keepdims=False, axis=None, dtype=None):
      return np.mean(
          np.square(input), keepdims=keepdims, axis=axis, dtype=dtype
      )
  
imports: import nvidia.dali.fn
  from nvidia.dali.pipeline import Pipeline
  from nose.tools import nottest
  import numpy
  from test_utils import np_type_to_dali
  from nose_utils import assert_raises
label_desc: Use image node_id 6 for calling a global function with example usage: np_mean_square(input, keepdims, axis, dtype) and returns: np