| bytes | Package bytes implements functions for the manipulation of byte slices. |
| encoding/binary | Package binary implements simple translation between numbers and byte sequences and encoding and decoding of varints. |
| errors | Package errors implements functions to manipulate errors. |
| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| io | Package io provides basic interfaces to I/O primitives. |
| math | Package math provides basic constants and mathematical functions. |
| reflect | Package reflect implements run-time reflection, allowing a program to manipulate objects with arbitrary 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. |