Package diff implements a linewise diff algorithm.
Diff returns a string containing a line-by-line unified diff of the linewise changes required to make A into B. Each line is prefixed with '+', '-', or ' ' to indicate if it should be added, removed, or is correct respectively.
Output: -:wq We the People of the United States, in Order to form a more perfect Union, establish Justice, insure domestic Tranquility, provide for the common defence, -and secure the Blessings of Liberty to ourselves +promote the general Welfare, and secure the Blessings of Liberty to ourselves and our Posterity, do ordain and establish this Constitution for the United States of America.
Chunk represents a piece of the diff. A chunk will not have both added and deleted lines. Equal lines are always after any added or deleted lines. A Chunk may or may not have any lines in it, especially for the first or last chunk in a computation.