Create a "summary" with ellipsis from a big string

truncate_with_suffix.py

def truncate(message, size, suffix='...'):
    '''Create message cutted with ellipses.

    >>> message = 'hello crazy world'
    >>> truncate(message, 1)
    ''
    >>> truncate(message, 9)
    'hello...'
    >>> truncate(message, 15)
    'hello crazy...'
    >>> truncate(message, 128)
    'hello crazy world'
    '''
    #max_size -= 1  # Count the index 0
    if len(message) >= size:
        rindex = size - len(suffix)
        if rindex > 0:
            message = message[:rindex]
            message = message[:message.rfind(' ')]
            message += suffix
        else:
            message = ''

    return message[:size]