Package builtin provides documentation for Go's predeclared identifiers.

Doc (usually run as go doc) accepts zero, one or two arguments.

Package fmt implements formatted I/O with functions analogous to C's printf and scanf.

Package io provides basic interfaces to I/O primitives.

Package io provides basic interfaces to I/O primitives.

Package os provides a platform-independent interface to operating system functionality.

Package regexp implements regular expression search.

Package sync provides basic synchronization primitives such as mutual exclusion locks.

Package testing provides support for automated testing of Go packages.

Package time provides functionality for measuring and displaying time.

Package unsafe contains operations that step around the type safety of Go programs.