func Imports(fset *token.FileSet, f *ast.File) [][]*ast.ImportSpec {
	var groups [][]*ast.ImportSpec

	for _, decl := range f.Decls {
		genDecl, ok := decl.(*ast.GenDecl)
		if !ok || genDecl.Tok != token.IMPORT {
			break
		}

		group := []*ast.ImportSpec{}

		var lastLine int
		for _, spec := range genDecl.Specs {
			importSpec := spec.(*ast.ImportSpec)
			pos := importSpec.Path.ValuePos
			line := fset.Position(pos).Line

		}
	}
	after(x)
}

// imports reports whether f imports path.
func imports(f *ast.File, path string) bool {
	return importSpec(f, path) != nil
}

// importSpec returns the import spec if f imports path,
// or nil otherwise.
func importSpec(f *ast.File, path string) *ast.ImportSpec {
	for _, s := range f.Imports {
		if importPath(s) == path {
			return s
		}
	}
	return nil
}

func findImportGroupStarts(imps []*ast.ImportSpec) []token.Pos {
	startImps := findImportGroupStarts1(imps)
	groupStarts := make([]token.Pos, len(startImps))
	for i, imp := range startImps {
		groupStarts[i] = imp.Pos()
	}
	return groupStarts
}

// Helper for findImportGroupStarts to ease testing.
func findImportGroupStarts1(origImps []*ast.ImportSpec) []*ast.ImportSpec {
	// Copy to avoid mutation.

	sawC := false
	for _, decl := range ast1.Decls {
		switch decl := decl.(type) {
		case *ast.GenDecl:
			for _, spec := range decl.Specs {
				s, ok := spec.(*ast.ImportSpec)
				if !ok || s.Path.Value != `"C"` {
					continue
				}
				sawC = true
				if s.Name != nil {
					error_(s.Path.Pos(), `cannot rename import "C"`)
				}
				cg := s.Doc

// constant, type, or variable declaration.
type (
	// The Spec type stands for any of *ImportSpec, *ValueSpec, and *TypeSpec.
	Spec interface {
		Node
		specNode()
	}

	// An ImportSpec node represents a single package import.
	ImportSpec struct {
		Doc     *CommentGroup // associated documentation; or nil
		Name    *Ident        // local package name (including "."); or nil

	case *ast.Ident:
		children = append(children,
			tok(n.NamePos, len(n.Name)))

	case *ast.IfStmt:
		children = append(children,
			tok(n.If, len("if")))

	case *ast.ImportSpec:
		// TODO(adonovan): ImportSpec.{Doc,EndPos}?

	case *ast.IncDecStmt:
		children = append(children,
			tok(n.TokPos, len(n.Tok.String())))

	case *ast.IndexExpr:
		children = append(children,

func renameImportPath(f *ast.File, renames ...string) {
	m := makeRenameMap(renames...)
	ast.Inspect(f, func(n ast.Node) bool {
		switch n := n.(type) {
		case *ast.ImportSpec:
			if n.Path.Kind != token.STRING {
				panic("invalid import path")
			}
			m.rename(&n.Path.Value)
			return false
		}
		return true
	})
}

		}

		// Add special dot-import declaration:
		//    import . "·this·"
		var decls []ast.Decl
		decls = append(decls, &ast.GenDecl{
			Tok: token.IMPORT,
			Specs: []ast.Spec{
				&ast.ImportSpec{
					Name: &ast.Ident{Name: "."},
					Path: &ast.BasicLit{
						Kind:  token.STRING,
						Value: strconv.Quote(thispkg),
					},
				},
			},
		})

	// Implicits maps nodes to their implicitly declared objects, if any.
	// The following node and object types may appear:
	//
	//     node               declared object
	//
	//     *ast.ImportSpec    *PkgName for imports without renames
	//     *ast.CaseClause    type-specific *Var for each type switch case clause (incl. default)
	//     *ast.Field         anonymous parameter *Var (incl. unnamed results)
	//

	}

	hasEmbed := false
	for _, decl := range info.parsed.Decls {
		d, ok := decl.(*ast.GenDecl)
		if !ok {
			continue
		}
		for _, dspec := range d.Specs {
			spec, ok := dspec.(*ast.ImportSpec)
			if !ok {
				continue
			}
			quoted := spec.Path.Value
			path, err := strconv.Unquote(quoted)
			if err != nil {
				return fmt.Errorf("parser returned invalid quoted string: <%s>", quoted)
			}