Extract ISBNs from a text.

    :param text: Some text.
    :returns: A list of canonical ISBNs found in the text.

    >>> extract_from_text("978-3-16-148410-0 9783161484100 9783161484100aa abcd 0136091814 0136091812 9780136091817 123456789X")
    ['9783161484100', '9783161484100', '9783161484100', '0136091814', '123456789X']

def extract_from_text(text):
    """
    Extract ISBNs from a text.

    :param text: Some text.
    :returns: A list of canonical ISBNs found in the text.

    >>> extract_from_text("978-3-16-148410-0 9783161484100 9783161484100aa abcd 0136091814 0136091812 9780136091817 123456789X")
    ['9783161484100', '9783161484100', '9783161484100', '0136091814', '123456789X']
    """
    isbns = [isbnlib.get_canonical_isbn(isbn)
             for isbn in isbnlib.get_isbnlike(text)]
    return [i for i in isbns if i is not None]