Rune is a superset of ASCII or it is an alias of int32. It holds all the characters available in the world’s writing system, including accents and other diacritical marks, control codes like tab and carriage return, and assigns each one a standard number. This standard number is known as a Unicode code point or rune in the Go language.
You are allowed to check the given rune is a letter or not with the help of IsLetter() function. This function returns true if the given rune is a letter, or return false if the given rune is not a letter. This function is defined under Unicode package, so for accessing this method you need to import the Unicode package in your program.
func IsLetter(r rune) bool
The return type of this function is boolean. Let us discuss this concept with the help of given examples:
true true false false true
It is a letter It is a letter It is not a letter It is a letter It is not a letter