nt to an "interesting" match.

Here's the same example as before, but considering blanks to be
junk.  That prevents " abcd" from matching the " abcd" at the tail
end of the second sequence directly.  Instead only the "abcd" can
match, and matches the leftmost "abcd" in the second sequence:

>>> s = SequenceMatcher(lambda x: x==" ", " abcd", "abcd abcd")
>>> s.find_longest_match(0, 5, 0, 9)
Match(a=1, b=0, size=4)

If no blocks match, return (alo, blo, 0).

>>> s = SequenceMatcher(None, "ab", "c")
>>> s.find_longest_match(0, 2, 0, 1)
Match(a=0, b=0, size=0)
r