def encode(self, word, max_length=6, modified=False):
        """Return the NYSIIS code for a word.

        Parameters
        ----------
        word : str
            The word to transform
        max_length : int
            The maximum length (default 6) of the code to return
        modified : bool
            Indicates whether to use USDA modified NYSIIS

        Returns
        -------
        str
            The NYSIIS value

        Examples
        --------
        >>> pe = NYSIIS()
        >>> pe.encode('Christopher')
        'CRASTA'
        >>> pe.encode('Niall')
        'NAL'
        >>> pe.encode('Smith')
        'SNAT'
        >>> pe.encode('Schmidt')
        'SNAD'

        >>> pe.encode('Christopher', max_length=-1)
        'CRASTAFAR'

        >>> pe.encode('Christopher', max_length=8, modified=True)
        'CRASTAFA'
        >>> pe.encode('Niall', max_length=8, modified=True)
        'NAL'
        >>> pe.encode('Smith', max_length=8, modified=True)
        'SNAT'
        >>> pe.encode('Schmidt', max_length=8, modified=True)
        'SNAD'

        """
        # Require a max_length of at least 6
        if max_length > -1:
            max_length = max(6, max_length)

        word = ''.join(c for c in word.upper() if c.isalpha())
        word = word.replace('ß', 'SS')

        # exit early if there are no alphas
        if not word:
            return ''

        original_first_char = word[0]

        if word[:3] == 'MAC':
            word = 'MCC' + word[3:]
        elif word[:2] == 'KN':
            word = 'NN' + word[2:]
        elif word[:1] == 'K':
            word = 'C' + word[1:]
        elif word[:2] in {'PH', 'PF'}:
            word = 'FF' + word[2:]
        elif word[:3] == 'SCH':
            word = 'SSS' + word[3:]
        elif modified:
            if word[:2] == 'WR':
                word = 'RR' + word[2:]
            elif word[:2] == 'RH':
                word = 'RR' + word[2:]
            elif word[:2] == 'DG':
                word = 'GG' + word[2:]
            elif word[:1] in self._uc_v_set:
                word = 'A' + word[1:]

        if modified and word[-1:] in {'S', 'Z'}:
            word = word[:-1]

        if (
            word[-2:] == 'EE'
            or word[-2:] == 'IE'
            or (modified and word[-2:] == 'YE')
        ):
            word = word[:-2] + 'Y'
        elif word[-2:] in {'DT', 'RT', 'RD'}:
            word = word[:-2] + 'D'
        elif word[-2:] in {'NT', 'ND'}:
            word = word[:-2] + ('N' if modified else 'D')
        elif modified:
            if word[-2:] == 'IX':
                word = word[:-2] + 'ICK'
            elif word[-2:] == 'EX':
                word = word[:-2] + 'ECK'
            elif word[-2:] in {'JR', 'SR'}:
                return 'ERROR'

        key = word[:1]

        skip = 0
        for i in range(1, len(word)):
            if i >= len(word):
                continue
            elif skip:
                skip -= 1
                continue
            elif word[i : i + 2] == 'EV':
                word = word[:i] + 'AF' + word[i + 2 :]
                skip = 1
            elif word[i] in self._uc_v_set:
                word = word[:i] + 'A' + word[i + 1 :]
            elif modified and i != len(word) - 1 and word[i] == 'Y':
                word = word[:i] + 'A' + word[i + 1 :]
            elif word[i] == 'Q':
                word = word[:i] + 'G' + word[i + 1 :]
            elif word[i] == 'Z':
                word = word[:i] + 'S' + word[i + 1 :]
            elif word[i] == 'M':
                word = word[:i] + 'N' + word[i + 1 :]
            elif word[i : i + 2] == 'KN':
                word = word[:i] + 'N' + word[i + 2 :]
            elif word[i] == 'K':
                word = word[:i] + 'C' + word[i + 1 :]
            elif modified and i == len(word) - 3 and word[i : i + 3] == 'SCH':
                word = word[:i] + 'SSA'
                skip = 2
            elif word[i : i + 3] == 'SCH':
                word = word[:i] + 'SSS' + word[i + 3 :]
                skip = 2
            elif modified and i == len(word) - 2 and word[i : i + 2] == 'SH':
                word = word[:i] + 'SA'
                skip = 1
            elif word[i : i + 2] == 'SH':
                word = word[:i] + 'SS' + word[i + 2 :]
                skip = 1
            elif word[i : i + 2] == 'PH':
                word = word[:i] + 'FF' + word[i + 2 :]
                skip = 1
            elif modified and word[i : i + 3] == 'GHT':
                word = word[:i] + 'TTT' + word[i + 3 :]
                skip = 2
            elif modified and word[i : i + 2] == 'DG':
                word = word[:i] + 'GG' + word[i + 2 :]
                skip = 1
            elif modified and word[i : i + 2] == 'WR':
                word = word[:i] + 'RR' + word[i + 2 :]
                skip = 1
            elif word[i] == 'H' and (
                word[i - 1] not in self._uc_v_set
                or word[i + 1 : i + 2] not in self._uc_v_set
            ):
                word = word[:i] + word[i - 1] + word[i + 1 :]
            elif word[i] == 'W' and word[i - 1] in self._uc_v_set:
                word = word[:i] + word[i - 1] + word[i + 1 :]

            if word[i : i + skip + 1] != key[-1:]:
                key += word[i : i + skip + 1]

        key = self._delete_consecutive_repeats(key)

        if key[-1:] == 'S':
            key = key[:-1]
        if key[-2:] == 'AY':
            key = key[:-2] + 'Y'
        if key[-1:] == 'A':
            key = key[:-1]
        if modified and key[:1] == 'A':
            key = original_first_char + key[1:]

        if max_length > 0:
            key = key[:max_length]

        return key
Return the NYSIIS code for a word.

        Parameters
        ----------
        word : str
            The word to transform
        max_length : int
            The maximum length (default 6) of the code to return
        modified : bool
            Indicates whether to use USDA modified NYSIIS

        Returns
        -------
        str
            The NYSIIS value

        Examples
        --------
        >>> pe = NYSIIS()
        >>> pe.encode('Christopher')
        'CRASTA'
        >>> pe.encode('Niall')
        'NAL'
        >>> pe.encode('Smith')
        'SNAT'
        >>> pe.encode('Schmidt')
        'SNAD'

        >>> pe.encode('Christopher', max_length=-1)
        'CRASTAFAR'

        >>> pe.encode('Christopher', max_length=8, modified=True)
        'CRASTAFA'
        >>> pe.encode('Niall', max_length=8, modified=True)
        'NAL'
        >>> pe.encode('Smith', max_length=8, modified=True)
        'SNAT'
        >>> pe.encode('Schmidt', max_length=8, modified=True)
        'SNAD'