Attempt to shorten a phrase by deleting words at the end of the phrase

    >>> shorten('Hello World!')
    'Hello World'
    >>> shorten("Hello World! I'll talk your ear off!", 15)
    'Hello World'

def shorten(s, max_len=16):
    """Attempt to shorten a phrase by deleting words at the end of the phrase

    >>> shorten('Hello World!')
    'Hello World'
    >>> shorten("Hello World! I'll talk your ear off!", 15)
    'Hello World'
    """
    short = s
    words = [abbreviate(word) for word in get_words(s)]
    for i in range(len(words), 0, -1):
        short = ' '.join(words[:i])
        if len(short) <= max_len:
            break
    return short[:max_len]