'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.'

@classmethod
def _is_latin_letter(cls, letter):

    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))
