standard-char-p character => generalized-boolean
character—a character.
generalized-boolean—a generalized boolean.
Returns true if character is of type standard-char; otherwise, returns false.
(standard-char-p #\Space) => true
(standard-char-p #\~) => true
;; This next example presupposes an implementation
;; in which #\Bell is a defined character.
(standard-char-p #\Bell) => false
Should signal an error of type type-error if character is not a character.