| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| 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/callgraph | Package callgraph defines the call graph and various algorithms and utilities to operate on it. |
| golang.org/x/tools/go/callgraph/vta/internal/trie | trie implements persistent Patricia trie maps. |
| golang.org/x/tools/go/ssa | Package ssa defines a representation of the elements of Go programs (packages, types, functions, variables and constants) using a static single-assignment (SSA) form intermediate representation (IR) for the bodies of functions. |
| golang.org/x/tools/go/types/typeutil | Package typeutil defines various utilities for types, such as Map, a hash table that maps types.Type to any value. |
| golang.org/x/tools/internal/typeparams | Package typeparams contains common utilities for writing tools that interact with generic Go code, as introduced with Go 1.18. |