code: def ref_all_gather(x_data, n_devices):
      results = []
      for i in range(n_devices):
          results.append(x_data * i)
      return results
  
imports: import pytest
  import nnabla
  import nnabla.parametric_functions
  import numpy
  from nnabla.testing import assert_allclose
label_desc: Use image node_id 1 for calling a global function with example usage: ref_all_gather(x_data, n_devices) and returns: results