| errors | Package errors implements functions to manipulate errors. |
| internal/fmtsort | Package fmtsort provides a general stable ordering mechanism for maps, on behalf of the fmt and text/template packages. |
| io | Package io provides basic interfaces to I/O primitives. |
| math | Package math provides basic constants and mathematical functions. |
| os | Package os provides a platform-independent interface to operating system functionality. |
| reflect | Package reflect implements run-time reflection, allowing a program to manipulate objects with arbitrary types. |
| sort | Package sort provides primitives for sorting slices and user-defined collections. |
| strconv | Package strconv implements conversions to and from string representations of basic data types. |
| sync | Package sync provides basic synchronization primitives such as mutual exclusion locks. |
| unicode/utf8 | Package utf8 implements functions and constants to support text encoded in UTF-8. |