code: def norm(x, order=None, axis=None):
      if axis is not None:
          return np.apply_along_axis(
              np.linalg.norm, axis, x.astype(np.float64), order
          )
  
      return np.linalg.norm(x.astype(np.float64), ord=order)
  
file_path: dipy/dipy/segment/tests/test_metric.py
imports: import itertools
  import numpy
  from numpy.testing import assert_array_equal, assert_raises, assert_almost_equal, assert_equal
  import dipy.segment.featurespeed
  import dipy.segment.metric
  import dipy.segment.metricspeed
  from dipy.testing import assert_true, assert_false, assert_greater_equal, assert_less_equal
  from dipy.testing.decorators import set_random_number_generator
label_desc: Use image node_id 1 for calling a global function with example usage: norm(x, order, axis) and returns: np, np