code: def ref_arange(start, stop, step):
      return np.arange(start, stop, step).astype(np.float32)
  
imports: import pytest
  import numpy
  import nnabla.functions
  from nbla_test_utils import list_context, function_tester
label_desc: Use image node_id 1 for calling a global function with example usage: ref_arange(start, stop, step) and returns: np