| context | Package context defines the Context type, which carries deadlines, cancellation signals, and other request-scoped values across API boundaries and between processes. |
| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| google.golang.org/appengine | Package appengine provides basic functionality for Google App Engine. |
| google.golang.org/appengine/internal | Package internal provides support for package appengine. |
| google.golang.org/appengine/internal/image | |
| net/url | Package url parses URLs and implements query escaping. |