/**
 * Checks if an argument is not an object
 * Note: will return false if input is an array, because arrays are objects in JavaScript
 * @param arg - parameter which should be verified
 */
export declare function isNotObject(arg: any): boolean;
/**
 * Checks if an argument is neither an object nor an array
 * @param arg - parameter which should be verified
 */
export declare function isNotObjectOrArray(arg: any): boolean;
/**
 * Checks if an argument is an object
 * Note: will return true if input is an array, because arrays are objects in JavaScript
 * @param arg - parameter which should be verified
 */
export declare function isObject(arg: any): boolean;
/**
 * Checks if an argument is either an object or an array
 * @param arg - parameter which should be verified
 */
export declare function isObjectOrArray(arg: any): boolean;
/**
 * Checks if a value is a valid value. That means not null, undefined, NaN.
 * @param arg - parameter which should be verified
 */
export declare function isValid(arg: any): boolean;
/**
 * Checks if a value is not a valid value. That means null, undefined, NaN.
 * @param arg - parameter which should be verified
 */
export declare function isNotValid(arg: any): boolean;
/**
 * Checks if an argument is null or if an object contains any
 * null values.
 * @param arg
 */
export declare function noNullValues(arg: any): boolean;
/**
 * Checks if an argument is null or if an object contains any
 * null values.
 *
 * Takes as optional argument an array of object keys. If keys are given
 * then only the arg[key]'s are checked for null values.
 * @param arg
 * @param keys
 */
export declare function notNull(arg: any, keys?: string[]): boolean;