Pangram

One popular pangram is "The quick brown fox jumps over the lazy dog."

Higher in the scale range the Cadmean curiosities of the Pangram, Lipogram, and Anagram. The first of these must contain the entire alphabet, and claims the twenty-first verse of the seventh chapter of the Prophet Ezra as its most noted example.

Like the search for the perfect palindrome, the pursuit of the perfect pangram has obsessed many people.

Write a Python function to determine whether or not a string is a pangram.

A pangram (or, as some manage, the triple pangram, with at least three of every letter) restricts the options, directing the setter away from habits and repetition and towards a fresher puzzle.

I've always wanted to make an anti-pangram pangram puzzle - the NYT would never run something so self-mocking!