>>> from letters import occurrences

>>> d = occurrences('Genius is 1% inspiration and 99% perspiration. Thomas Edison.')
>>> if d != {'g': 1, 'e': 3, 'n': 6, 'i': 8, 'u': 1, 's': 6, '1': 1, 'p': 3,
...       'r': 3, 'a': 4, 't': 3, 'o': 4, 'd': 2, '9': 2, 'h': 1, 'm': 1}:
...    print(d)

>>> d = occurrences("I'm gonna make him an offer he can't refuse. Vito Corleone.")
>>> if d != {'i': 3, 'm': 3, 'g': 1, 'o': 5, 'n': 5, 'a': 4, 'k': 1, 'e': 7,
...    'h': 2, 'f': 3, 'r': 3, 'c': 2, 't': 2, 'u': 1, 's': 1, 'v': 1, 'l': 1}:
...    print(d)

>>> d = occurrences('Three can keep a secret, if two of them are dead. Benjamin Franklin')
>>> if d != {'t': 4, 'h': 2, 'r': 4, 'e': 10, 'c': 2, 'a': 6, 'n': 5, 'k': 2,
...       'p': 1, 's': 1, 'i': 3, 'f': 3, 'w': 1, 'o': 2, 'm': 2, 'd': 2,
...       'b': 1, 'j': 1, 'l': 1}:
...    print(d)

>>> d = occurrences('U.S. Route 61 (US 61), 1400 miles of blues')
>>> if d != {'u': 4, 's': 4, 'r': 1, 'o': 2, 't': 1, 'e': 3, '6': 2, '1': 3,
...       '4': 1, '0': 2, 'm': 1, 'i': 1, 'l': 2, 'f': 1, 'b': 1}:
...    print(d)