| flag | Package flag implements command-line flag parsing. |
| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| github.com/stretchr/testify/assert | Package assert provides a set of comprehensive testing tools for use with the normal Go testing system. |
| github.com/stretchr/testify/require | Package require implements the same assertions as the `assert` package but stops test execution when a test fails. |
| os | Package os provides a platform-independent interface to operating system functionality. |
| reflect | Package reflect implements run-time reflection, allowing a program to manipulate objects with arbitrary types. |
| regexp | Package regexp implements regular expression search. |
| runtime/debug | Package debug contains facilities for programs to debug themselves while they are running. |
| sync | Package sync provides basic synchronization primitives such as mutual exclusion locks. |
| testing | Package testing provides support for automated testing of Go packages. |