>return x >= 'A'; already and only means ascii A.

See, here's where you are wrong.

  ASCII_A = "A"

  alphas = ["Α", "А", "Ꭺ", "ᗅ", "ꓮ", "Ａ", "𐊠", "A", "𝐀", "𝖠", "𝙰", "𝚨", "𝝖"]

  for c in alphas:
      print c == ASCII_A

Output?

  False
  False
  False
  False
  False
  False
  False
  True
  False
  False
  False
  False
  False

Several of the numerous possible utf-8 alphas. Those are not A in different fonts -- they are different unicode characters that look like A. And depending on your font they could look absolutely the same as plain ascii a (of which only one towards the middle of the list is). And depending on your locale and keyboard language settings, one of them could be as easy to click as the regular english A in ASCII.

I deliberately used the character literal ‘A’ and not any of your UTF8 strings. I think you are mistaken to confuse a character with your strings. Is this wrong?

You can have a unicode character literal -- and depending on the language there's no distinction between character and string (at the type level), a character is just a string of length 1.

I was assuming C, where there is a difference.

int main() { printf( "%d %d\n", 'A', "A" ); return 0; }

produces: 65 197730221

since the value of string "A" is its base address.