| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| github.com/pkg/errors | Package errors provides simple error handling primitives. |
| io | Package io provides basic interfaces to I/O primitives. |
| math | Package math provides basic constants and mathematical functions. |
| 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. |
| unsafe | Package unsafe contains operations that step around the type safety of Go programs. |