/**
 * be aware of s[s.length] --> undefined
 * */
export type CharChecker = (c: string) => boolean;
export declare const isDigit: CharChecker;
export declare const isLowerCase: CharChecker;
export declare const isUpperCase: CharChecker;
export declare const isAlphabet: CharChecker;
export declare const isWhiteSpace: CharChecker;
export declare const isLineBreak: CharChecker;