| bytes | Package bytes implements functions for the manipulation of byte slices. |
| errors | Package errors implements functions to manipulate errors. |
| os | Package os provides a platform-independent interface to operating system functionality. |
| runtime | Package runtime contains operations that interact with Go's runtime system, such as functions to control goroutines. |
| sort | Package sort provides primitives for sorting slices and user-defined collections. |
| strings | Package strings implements simple functions to manipulate UTF-8 encoded strings. |
| unicode/utf8 | Package utf8 implements functions and constants to support text encoded in UTF-8. |