export declare function assertMaybeString(name: string, mixed: any): (null | undefined | (string)) | never;
export declare function assertMaybeMinLength(name: string, mixed: any, min: number): (null | undefined | (string)) | never;
export declare function assertMaybeMinLengthHandler(min: number): (name: string, mixed: any) => (null | undefined | (string)) | never;
export declare function assertMaybeMaxLength(name: string, mixed: any, max: number): (null | undefined | (string)) | never;
export declare function assertMaybeMaxLengthHandler(max: number): (name: string, mixed: any) => (null | undefined | (string)) | never;
export declare function assertMaybeLength(name: string, mixed: any, args: {
    min?: number;
    max?: number;
}): (null | undefined | (string)) | never;
export declare function assertMaybeLengthHandler(args: {
    min?: number;
    max?: number;
}): (name: string, mixed: any) => (null | undefined | (string)) | never;
export declare function assertMaybeNonEmpty(name: string, mixed: any): (null | undefined | (string)) | never;
export declare function assertMaybeContains(name: string, mixed: any, x: string): (null | undefined | (string)) | never;
export declare function assertMaybeContainsHandler(x: string): (name: string, mixed: any) => (null | undefined | (string)) | never;
export declare function assertMaybeNoDuplicate(name: string, mixed: any): (null | undefined | (string)) | never;
export declare function assertMaybeNotAllWhitespace(name: string, mixed: any): (null | undefined | (string)) | never;
export declare function assertMaybeNonEmptyAndNotAllWhitespace(name: string, mixed: any): (null | undefined | (string)) | never;
export declare function assertMaybeMatch(name: string, mixed: any, regex: RegExp): (null | undefined | (string)) | never;
export declare function assertMaybeMatchHandler(regex: RegExp): (name: string, mixed: any) => (null | undefined | (string)) | never;
export declare function assertMaybeEmail(name: string, mixed: any): (null | undefined | (string)) | never;
export declare function assertMaybeNotOneOf<T extends string>(name: string, mixed: any, arr: T[]): (null | undefined | (string)) | never;
export declare function assertMaybeNotOneOfHandler<T extends string>(arr: T[]): (name: string, mixed: any) => (null | undefined | (string)) | never;
export declare function assertMaybeBase64(name: string, mixed: any): (null | undefined | (string)) | never;
export declare function assertMaybeJson(name: string, mixed: any): (null | undefined | (string)) | never;