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

controlType: 'ordinalColors',
        group: 'Style',
    },
    {
        key: 'colorBy',
        type: 'string | Function',
        help: 'Property used to determine node color.',
        description: `
            Property to use to determine node color.
            If a function is provided, it will receive
            the current node data and must return
            a string or number which will be passed
            to the color generator.
        `,
        required: false,
        defaultValue: defaults.colorBy,
        controlType: 'choices',
        group: 'Style',
        controlOptions: {
            choices: [
                {
                    label: 'id',
                    value: 'id',
                },
                {
                    label: 'index',
                    value: 'index',
                },
            ],
        },
    },
    {