code: def _is_latin_letter(cls, letter):
          
          # Combining marks are a subset of non-spacing-mark
          if (not is_letter(letter) and
              Category.get(letter) != Category.NON_SPACING_MARK):
              return False
          block = Block.get(letter)
          return (block == Block.BASIC_LATIN or
                  block == Block.LATIN_1_SUPPLEMENT or
                  block == Block.LATIN_EXTENDED_A or
                  block == Block.LATIN_EXTENDED_ADDITIONAL or
                  block == Block.LATIN_EXTENDED_B or
                  block == Block.COMBINING_DIACRITICAL_MARKS)
docs: Helper method to determine if a character is a Latin-script letter
          or not. For our purposes, combining marks should also return True
          since we assume they have been added to a preceding Latin character.