| encoding/binary | Package binary implements simple translation between numbers and byte sequences and encoding and decoding of varints. |
| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| golang.org/x/text/transform | Package transform provides reader and writer wrappers that transform the bytes passing through as well as various transformations. |
| io | Package io provides basic interfaces to I/O primitives. |
| 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. |