| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| golang.org/x/text/language | Package language implements BCP 47 language tags and related functionality. |
| golang.org/x/text/unicode/norm | Package norm contains types and functions for normalizing Unicode strings. |
| sort | Package sort provides primitives for sorting slices and user-defined collections. |
| unicode | Package unicode provides data and functions to test some properties of Unicode code points. |
| unicode/utf8 | Package utf8 implements functions and constants to support text encoded in UTF-8. |