| 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. |
| io | Package io provides basic interfaces to I/O primitives. |
| math/bits | Package bits implements bit counting and manipulation functions for the predeclared unsigned integer types. |
| runtime | Package runtime contains operations that interact with Go's runtime system, such as functions to control goroutines. |