code: def convert_Stack(
      func, opset_version, input_names, output_names, context
  ):
      gb = onnx_helper.GraphBuilder()
      axis = func.axis
      if axis < 0:
          axis = len(func.inputs[0].shape) + 1 + axis
  
      # To use concat op, reshape every inputs add new axes
      inputs = [
          gb.op("Unsqueeze", [name], axes=[axis])
          for name in input_names
      ]
      gb.op_output_named("Concat", inputs, output_names, axis=axis)
      return gb.nodes()
  
imports: import warnings
  import chainer
  import numpy
  import onnx
  from onnx.mapping import NP_TYPE_TO_TENSOR_TYPE
  from onnx_chainer.functions.opset_version import support
  from onnx_chainer import onnx_helper
label_desc: Use image node_id 22 for calling a global function with example usage: convert_Stack(func, opset_version, input_names, output_names, context) and returns: gb