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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _is_latin_letter(cls, letter):
 """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."""

        # 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)