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


function pangram(string s)
sequence az = repeat(false,26)
integer count = 0
    for i=1 to length(s) do
        integer ch = lower(s[i])
        if ch>='a'
        and ch<='z'
        and not az[ch-96] then
            count += 1
            if count=26 then return {true,0} end if
            az[ch-96] = true
        end if
    end for
    return {false,find(false,az)+96}
end function
 
sequence checks = {"The quick brown fox jumped over the lazy dog",
                   "The quick brown fox jumps over the lazy dog",
                   ".!$\"AbCdEfghijklmnoprqstuvwxyz",
                   "THE FIVE BOXING WIZARDS DUMP QUICKLY.",
                   "THE FIVE BOXING WIZARDS JUMP QUICKLY.",
                   "HEAVY BOXES PERFORM WALTZES AND JIGS.",
                   "PACK MY BOX WITH FIVE DOZEN LIQUOR JUGS.",
                   "Big fjiords vex quick waltz nymph",
                   "The quick onyx goblin jumps over the lazy dwarf.",
                   "no"}
for i=1 to length(checks) do
    string ci = checks[i]
    integer {r,ch} = pangram(ci)
    printf(1,"%-50s - %s\n",{ci,iff(r?"yes":"no "&ch)})
end for
