| bytes | Package bytes implements functions for the manipulation of byte slices. |
| 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. |
| regexp | Package regexp implements regular expression search. |
| sync | Package sync provides basic synchronization primitives such as mutual exclusion locks. |
| unicode | Package unicode provides data and functions to test some properties of Unicode code points. |