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


define Eng = 'a'..'z';
define Hex = 'a'..'f';
define Cyr = %w(а б в г д е ж з и й к л м н о п р с т у ф х ц ч ш щ ъ ы ь э ю я ё);
 
func pangram(str, alpha=Eng) {
    var lstr = str.lc;
    alpha.all {|c| lstr.contains(c) };
}
 
say pangram("The quick brown fox jumps over the lazy dog.");
say pangram("My dog has fleas.");
say pangram("My dog has fleas.", Hex);
say pangram("My dog backs fleas.", Hex);
say pangram("Съешь же ещё этих мягких французских булок, да выпей чаю", Cyr);