| flag | Package flag implements command-line flag parsing. |
| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| go/build | Package build gathers information about Go packages. |
| golang.org/x/tools/go/buildutil | Package buildutil provides utilities related to the go/build package in the standard library. |
| golang.org/x/tools/refactor/rename | Package rename contains the implementation of the 'gorename' command whose main function is in golang.org/x/tools/cmd/gorename. |
| log | Package log implements a simple logging package. |
| os | Package os provides a platform-independent interface to operating system functionality. |