| errors | Package errors implements functions to manipulate errors. |
| internal/reflectlite | Package reflectlite implements lightweight version of reflect, not using any package except for "runtime", "unsafe", and "internal/abi" |
| sync | Package sync provides basic synchronization primitives such as mutual exclusion locks. |
| sync/atomic | Package atomic provides low-level atomic memory primitives useful for implementing synchronization algorithms. |
| time | Package time provides functionality for measuring and displaying time. |