| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| golang.org/x/mobile/internal/mobileinit | Package mobileinit contains common initialization logic for mobile platforms that is relevant to both all-Go apps and gobind-based apps. |
| runtime | Package runtime contains operations that interact with Go's runtime system, such as functions to control goroutines. |
| sync | Package sync provides basic synchronization primitives such as mutual exclusion locks. |
| unicode/utf16 | Package utf16 implements encoding and decoding of UTF-16 sequences. |