code: def test_cat_all_empty():
      pipe = dali.pipeline.Pipeline(
          batch_size=1, num_threads=3, device_id=0
      )
      with pipe:
          src1 = dali.types.Constant(
              np.array([[], [], []], dtype=np.int32)
          )
          out_cpu = fn.cat(src1, src1, src1, axis=1)
          out_gpu = fn.cat(src1.gpu(), src1.gpu(), src1.gpu(), axis=1)
          pipe.set_outputs(out_cpu, out_gpu)
  
      pipe.build()
      o = pipe.run()
  
      o = list(o)
      o[1] = o[1].as_cpu()
  
      ref = np.array([[], [], []], dtype=np.int32)
      assert np.array_equal(o[0].at(0), ref)
      assert np.array_equal(o[1].at(0), ref)
  
file_path: DALI/dali/test/python/operator_1/test_join.py
imports: import nvidia.dali
  import nvidia.dali.fn
  import numpy
  import math
  from test_utils import check_batch
label_desc: Use image node_id 4 for calling a global function with example usage: test_cat_all_empty() without return types