Example from Hunt and McIlroy, “An Algorithm for Differential File Comparison.”

https://www.cs.dartmouth.edu/~doug/diff.pdf

-- old --

a

b

c

d

e

f

g

-- new --

w

a

b

x

y

z

e

-- diff --

diff old new

--- old

+++ new

@@ -1,7 +1,7 @@

+w

a

b

-c

-d

+x

+y

+z

e

-f

-g