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


let pangram str =
  let ar = Array.make 26 false in
  String.iter (function
  | 'a'..'z' as c -> ar.(Char.code c - Char.code 'a') <- true
  | _ -> ()
  ) (String.lowercase str);
  Array.fold_left ( && ) true ar