Generate nonsense words out of integers

# Port of rufus-mnemo to Python
# https://github.com/jmettraux/rufus-mnemo
# Original copyright (c) 2007-2011, John Mettraux, jmettraux@gmail.com

consonants = list('bdghjkmnprstz')
vowels = list('aeiou')
syllables = [c + v for c in consonants for v in vowels] + ['wa', 'wo', 'ya', 'yo', 'yu']
negative = 'wi'

replacements = [
    [ 'hu', 'fu' ],
    [ 'si', 'shi' ],
    [ 'ti', 'chi' ],
    [ 'tu', 'tsu' ],
    [ 'zi', 'tzu' ],
]

def encode(i):
    """
    Convert an integer to a base-70 gibberish string.
    """
    if i == 0:
        return ''

    mod = abs(i) % len(syllables)
    rest = abs(i) / len(syllables)

    result = ''.join([
        ['', negative][i < 0],
        encode(rest),
        syllables[mod],
    ])
    for old, new in replacements:
        result = result.replace(old, new)
    return result

def decode(s):
    """
    Convert a base-70 gibberish string back to an integer.
    """
    if not s:
        return 0

    if s.startswith(negative):
        return -1 * decode(s[len(negative):])

    for new, old in replacements:
        s = s.replace(old, new)

    rest = syllables.index(s[-2:]) if s[-2:] else 0
    return len(syllables) * decode(s[0:-2]) + rest