| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| github.com/go-kit/log | Package log provides a structured logger. |
| github.com/go-kit/log/level | Package level implements leveled logging on top of Go kit's log package. |
| os | Package os provides a platform-independent interface to operating system functionality. |
| sync | Package sync provides basic synchronization primitives such as mutual exclusion locks. |
| time | Package time provides functionality for measuring and displaying time. |