Pangram checker

You are encouraged to solve this task according to the task description, using any language you may know.
A pangram is a sentence that contains all the letters of the English alphabet at least once.

For example:   The quick brown fox jumps over the lazy dog.



Task

Write a function or method to check a sentence to see if it is a   pangram   (or not)   and show its use.



Related tasks

   determine if a string has all the same characters
   determine if a string has all unique characters


 
(context 'PGR)                              ;; Switch to context (say namespace) PGR
(define (is-pangram? str)
    (setf chars (explode (upper-case str))) ;; Uppercase + convert string into a list of chars
    (setf is-pangram-status true)           ;; Default return value of function
    (for (c (char "A") (char "Z") 1 (nil? is-pangram-status)) ;; For loop with break condition
        (if (not (find (char c) chars))     ;; If char not found in list, "is-pangram-status" becomes "nil"
            (setf is-pangram-status nil)
        )
    )
    is-pangram-status                       ;; Return current value of symbol "is-pangram-status"
)
(context 'MAIN)                             ;; Back to MAIN context
 
;; - - - - - - - - - -
 
(println (PGR:is-pangram? "abcdefghijklmnopqrstuvwxyz"))  ;; Print true
(println (PGR:is-pangram? "abcdef"))  ;; Print nil
(exit)
 