export declare const hasKey: (obj: Record<string, unknown>, key: string) => boolean;
export declare const isNull: (x: any) => boolean;
export declare const isObject: (x: any) => boolean;
export declare const isNumber: (x: any) => boolean;
export declare const isBoolean: (x: any) => boolean;
export declare const isString: (x: any) => boolean;
export declare const isArray: (arr: any) => boolean;
export declare const stringContains: (doesThis: string, containThis: string) => boolean;