| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| math/bits | Package bits implements bit counting and manipulation functions for the predeclared unsigned integer types. |
| strconv | Package strconv implements conversions to and from string representations of basic data types. |
| strings | Package strings implements simple functions to manipulate UTF-8 encoded strings. |
| sync/atomic | Package atomic provides low-level atomic memory primitives useful for implementing synchronization algorithms. |