code: def convert_ExpandDims(
      func, opset_version, input_names, output_names, context
  ):
      axis = func.axis
      if axis < 0:
          axis = len(func.inputs[0].shape) + 1 + axis
  
      return (
          onnx_helper.make_node(
              "Unsqueeze", input_names, output_names, axes=[axis]
          ),
      )
  
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 18 for calling a global function with example usage: convert_ExpandDims(func, opset_version, input_names, output_names, context) and returns: onnx_helper