| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| github.com/docker/distribution/context | Package context provides several utilities for working with Go's context in http requests. |
| io | Package io provides basic interfaces to I/O primitives. |
| regexp | Package regexp implements regular expression search. |
| strconv | Package strconv implements conversions to and from string representations of basic data types. |
| strings | Package strings implements simple functions to manipulate UTF-8 encoded strings. |
| time | Package time provides functionality for measuring and displaying time. |