How to use the @nivo/radar.RadarDefaultProps.borderColor function in @nivo/radar

},
    {
        key: 'borderWidth',
        help: 'Shape border width.',
        type: 'number',
        required: false,
        defaultValue: defaults.borderWidth,
        controlType: 'lineWidth',
        group: 'Style',
    },
    {
        key: 'borderColor',
        help: 'Method to compute border color.',
        type: 'string | object | Function',
        required: false,
        defaultValue: defaults.borderColor,
        controlType: 'inheritedColor',
        group: 'Style',
    },
    {
        key: 'gridLevels',
        help: 'Number of levels to display for grid',
        type: 'number',
        required: false,
        defaultValue: defaults.gridLevels,
        controlType: 'range',
        group: 'Grid',
        controlOptions: {
            min: 1,
            max: 12,
        },
    },