Return last nonblank character in a string.

Compiled as Common Lisp using GNU CLISP.

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"foo"  ⟹ "o"
"foo " ⟹ "o"

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(defun last-nonblank (str)
  (subseq (string-right-trim '(#\Space) str)
    (- (length (string-right-trim '(#\Space) str)) 1)))