All the kata is in english, it is safe to assume the language/alphabet used is english too. It should be noted if that wasn't the case.

I want to make a point, that "pangram" means a sentence using all letters from ONE language. As there are many languages using different alphabets, it's not obvious (cuz not specified in detials section) for which language we should check (english is not the only one languge in the world) or if we should detect it. For example: "The quick brown fox jumps over the lazy dog" is pangram in engilsh but it isn't in polish ¯_(ツ)_/¯.

I ignore the fact that pangram is about sentences, but details says "Ignore numbers and punctuation.", where sentence is actually a string endend with some "punctuation".