///|
fn normalize_ascii_letters(input : String) -> String {
  let mut normalized = ""
  for i = 0; i < input.length(); i = i + 1 {
    let code = input[i]
    if code >= 65 && code <= 90 {
      normalized = normalized + code.unsafe_to_char().to_string()
    } else if code >= 97 && code <= 122 {
      normalized = normalized + (code - 32).unsafe_to_char().to_string()
    }
  }
  normalized
}