Map MXNet's convolution operator attributes to onnx's Conv operator
    and return the created node.

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

    kernel_dims = list(parse_helper(attrs, "kernel"))
    stride_dims = list(parse_helper(attrs, "stride", [1, 1]))
    pad_dims = list(parse_helper(attrs, "pad", [0, 0]))
    num_group = int(attrs.get("num_group", 1))
    dilations = list(parse_helper(attrs, "dilate", [1, 1]))

    pad_dims = pad_dims + pad_dims

    conv_node = onnx.helper.make_node(
        "Conv",
        inputs=input_nodes,
        outputs=[name],
        kernel_shape=kernel_dims,
        strides=stride_dims,
        dilations=dilations,
        pads=pad_dims,
        group=num_group,
        name=name
    )

    return [conv_node]