= pd.Series(['foojpgbar.jpg'])
    >>> s.str.split(r".", expand=True)
               0    1
    0  foojpgbar  jpg

    >>> s.str.split(r"\.jpg", expand=True)
               0 1
    0  foojpgbar

    When ``regex=True``, `pat` is interpreted as a regex

    >>> s.str.split(r"\.jpg", regex=True, expand=True)
               0 1
    0  foojpgbar

    A compiled regex can be passed as `pat`

    >>> import re
    >>> s.str.split(re.compile(r"\.jpg"), expand=True)
               0 1
    0  foojpgbar

    When ``regex=False``, `pat` is interpreted as the string itself

    >>> s.str.split(r"\.jpg", regex=False, expand=True)
                   0
    0  foojpgbar.jpg
    )Ú