| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| golang.org/x/text/internal | Package internal contains non-exported functionality that are used by packages in the text repository. |
| golang.org/x/text/internal/format | Package format contains types for defining language-specific formatting of values. |
| golang.org/x/text/language | Package language implements BCP 47 language tags and related functionality. |
| io | Package io provides basic interfaces to I/O primitives. |
| strings | Package strings implements simple functions to manipulate UTF-8 encoded strings. |
| sync | Package sync provides basic synchronization primitives such as mutual exclusion locks. |