diff

assert(diff("abc", "abc") == tuple("abc", "abc"));
// highlight difference
assert(diff("abc", "Abc") == tuple("<a>bc", "<A>bc"));
assert(diff("abc", "aBc") == tuple("a<b>c", "a<B>c"));
assert(diff("abc", "abC") == tuple("ab<c>", "ab<C>"));
assert(diff("abc", "") == tuple("<abc>", "<>"));
assert(diff("abc", "abbc") == tuple("ab<>c", "ab<b>c"));
// abbreviate long prefix or suffix
assert(diff("_12345678901234567890a", "_12345678901234567890A")
		== tuple("...12345678901234567890<a>", "...12345678901234567890<A>"));
assert(diff("a12345678901234567890_", "A12345678901234567890_")
		== tuple("<a>12345678901234567890...", "<A>12345678901234567890..."));