| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| go.opencensus.io/stats/view | Package view contains support for collecting and exposing aggregates over stats. |
| go.opencensus.io/trace | Package trace contains support for OpenCensus distributed tracing. |
| gocloud.dev/gcerrors | Package gcerrors provides support for getting error codes from errors returned by Go CDK APIs. |
| log | Package log implements a simple logging package. |
| strings | Package strings implements simple functions to manipulate UTF-8 encoded strings. |
| sync | Package sync provides basic synchronization primitives such as mutual exclusion locks. |
| time | Package time provides functionality for measuring and displaying time. |