| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| go/ast | Package ast declares the types used to represent syntax trees for Go packages. |
| go/parser | Package parser implements a parser for Go source files. |
| go/scanner | Package scanner implements a scanner for Go source text. |
| go/token | Package token defines constants representing the lexical tokens of the Go programming language and basic operations on tokens (printing, predicates). |
| go/types | Package types declares the data types and implements the algorithms for type-checking of Go packages. |
| golang.org/x/tools/go/gcexportdata | Package gcexportdata provides functions for reading and writing export data, which is a serialized description of the API of a Go package including the names, kinds, types, and locations of all exported declarations. |
| golang.org/x/tools/go/packages | Package packages loads Go packages for inspection and analysis. |
| log | Package log implements a simple logging 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. |