Map MXNet's argmax operator attributes to onnx's ArgMax operator
    and return the created node.

def convert_argmax(node, **kwargs):
    """Map MXNet's argmax operator attributes to onnx's ArgMax operator
    and return the created node.
    """
    name, input_nodes, attrs = get_inputs(node, kwargs)

    axis = int(attrs.get("axis"))
    keepdims = get_boolean_attribute_value(attrs, "keepdims")

    node = onnx.helper.make_node(
        'ArgMax',
        inputs=input_nodes,
        axis=axis,
        keepdims=keepdims,
        outputs=[name],
        name=name
    )
    return [node]