How to use the @nivo/bar.BarDefaultProps.layers function in @nivo/bar

{
        key: 'layers',
        flavors: ['svg'],
        help: 'Defines the order of layers.',
        description: `
            Defines the order of layers, available layers are:
            \`grid\`, \`axes\`, \`bars\`, \`markers\`, \`legends\`.

            You can also use this to insert extra layers to the chart,
            this extra layer must be a function which will receive
            the chart computed data and must return a valid SVG
            element.
        `,
        type: 'Array',
        required: false,
        defaultValue: defaults.layers,
        group: 'Customization',
    },
    {
        key: 'enableLabel',
        help: 'Enable/disable labels.',
        type: 'boolean',
        required: false,
        defaultValue: defaults.enableLabel,
        controlType: 'switch',
        group: 'Labels',
    },
    {
        key: 'label',
        group: 'Labels',
        help: 'Define how bar labels are computed.',
        description: `