Diff returns a string containing a line-by-line unified diff of the linewise changes required to make A into B.

DiffChunks uses an O(D(N+M)) shortest-edit-script algorithm to compute the edits required from A to B and returns the edit chunks.

Render renders the slice of chunks into a representation that prefixes the lines with '+', '-', or ' ' depending on whether the line was added, removed, or equal (respectively).

Chunk represents a piece of the diff.