Truncate a string at the nearest delimiter to a certain length.

truncate_on.py

def truncate_on(string, length, delimiter=' '):
    """Truncate a string at the nearest delimiter to a certain length."""
    length = int(length)
    if len(string) > length:
        index = string.rfind(delimiter, 0, length)
        if index == -1:
            string = string[:50]
        else:
            string = string[:index]
    return string