| context | Package context defines the Context type, which carries deadlines, cancellation signals, and other request-scoped values across API boundaries and between processes. |
| crypto/rand | Package rand implements a cryptographically secure random number generator. |
| 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. |
| math/rand | Package rand implements pseudo-random number generators suitable for tasks such as simulation, but it should not be used for security-sensitive work. |
| runtime | Package runtime contains operations that interact with Go's runtime system, such as functions to control goroutines. |
| sync | Package sync provides basic synchronization primitives such as mutual exclusion locks. |
| time | Package time provides functionality for measuring and displaying time. |