ular  sentence
    1  https://docs.python.org/3/tutorial/index.html  None  None     None      None
    2                                            NaN   NaN   NaN      NaN       NaN

    For slightly more complex use cases like splitting the html document name
    from a url, a combination of parameter settings can be used.

    >>> s.str.rsplit("/", n=1, expand=True)
                                        0           1
    0          this is a regular sentence        None
    1  https://docs.python.org/3/tutorial  index.html
    2                                 NaN         NaN
    %(regex_examples)sZ	str_splitZ	beginningz