Grind polishes Go programs. Usage: Grind rewrites the source files in the named packages. When grind rewrites a file, it prints a line to standard error giving the name of the file and the rewrites applied. As a special case, if the arguments are a list of Go source files, they are considered to make up a single package, which is then rewritten. If the -diff flag is set, no files are rewritten. Instead grind prints the differences a rewrite would introduce. Grind does not make backup copies of the files that it edits. Instead, use a version control system's “diff” functionality to inspect the changes that grind makes before committing them.