/**
 * Validates that a channel value is a valid number within the range of 0 to 255.
 * Throws an error if the value is not valid.
 *
 * @param channelName - The name of the channel being validated.
 * @param value - The value of the channel to validate.
 * @throws Will throw an error if the value is not a valid channel number.
 *
 * @private util of `@promptbook/color`
 */
export declare function checkChannelValue(channelName: string, value: number): asserts value is number;