export interface Precondition {
    /** The target precondition header field. */
    readonly header: string;
    readonly evaluate: EvaluateCallback;
    readonly respond: RespondCallback;
}
export interface EvaluateContext {
    readonly fieldValue: string;
}
export interface EvaluateCallback {
    (request: Request, response: Response, context: EvaluateContext): boolean | Promise<boolean>;
}
export interface RespondCallback {
    (request: Request): Response | Promise<Response>;
}