function nextChar(char : string) : string {
return String.fromCharCode(char.charCodeAt(0) + 1);
}
console.log(nextChar('a'));
console.log(nextChar('b'));
console.log(nextChar('c'));
console.log(nextChar('A'));
console.log(nextChar('B'));
console.log(nextChar('C'));
/*
run:
"b"
"c"
"d"
"B"
"C"
"D"
*/