// src is the input that we want to tokenize.
	src := []byte("cos(x) + 1i*sin(x) // Euler")

	// Initialize the scanner.
	var s scanner.Scanner
	fset := token.NewFileSet()                      // positions are relative to fset
	file := fset.AddFile("", fset.Base(), len(src)) // register input "file"
	s.Init(file, src, nil /* no error handler */, scanner.ScanComments)

}

// addLines adds n lines to the position of b.
// n can be negative.
func addLines(b md.Block, n int) {
	pos := position(b)
	pos.StartLine += n
	pos.EndLine += n
}

func position(b md.Block) *md.Position {
	switch b := b.(type) {
	case *md.Heading:
		return &b.Position
	case *md.Text:
		return &b.Position
	case *md.CodeBlock:
		return &b.Position
	case *md.HTMLBlock:
		return &b.Position

	// By scanning backward, we can keep track of whether the current
	// position is type-S or type-L according to the usual definition:
	//
	//	- position len(text) is type S with text[len(text)] == -1 (the sentinel)
	//	- position i is type S if text[i] < text[i+1], or if text[i] == text[i+1] && i+1 is type S.
	//	- position i is type L if text[i] > text[i+1], or if text[i] == text[i+1] && i+1 is type L.
	//

		err = fmt.Errorf("invalid archive header")
		return
	}
	name = strings.TrimSpace(string(hdr[:16]))
	return
}

// FindExportData positions the reader r at the beginning of the
// export data section of an underlying GC-created object/archive
// file by reading from it. The reader must be positioned at the
// start of the file before calling this function. The hdr result
// is the string before the export data, either "$$" or "$$B".

			t.Fatal(err)
		}
		if pkg.Path() != thePackage {
			t.Fatalf("Path() = %q, want %q", pkg.Path(), thePackage)
		}

		// Check that the fileset positions are accurate.
		// https://github.com/golang/go#28995
		mathBigInt := pkg.Scope().Lookup("Int")
		posn := fset.Position(mathBigInt.Pos()) // "$GOROOT/src/math/big/int.go:25:1"
		filename := strings.Replace(posn.Filename, "$GOROOT", testenv.GOROOT(t), 1)
		data, err := os.ReadFile(filename)

	// builtin len:
	//   defined at <unknown position>
	//   used at 6:15
	// func fib(x int) int:
	//   defined at fib:8:6
	//   used at 12:20, 12:9
	// type S string:
	//   defined at fib:4:6
	//   used at 6:23
	// type int:
	//   defined at <unknown position>
	//   used at 8:12, 8:17
	// type string:
	//   defined at <unknown position>
	//   used at 4:8
	// var b S:
	//   defined at fib:6:8

		if offsetBeginString[0] == '+' {
			return nil, fmt.Errorf("Byte position ('%s') must not have a sign", offsetBeginString)
		} else if offsetBegin, err = strconv.ParseInt(offsetBeginString, 10, 64); err != nil {
			return nil, fmt.Errorf("'%s' does not have a valid first byte position value", rangeString)
		} else if offsetBegin < 0 {
			return nil, fmt.Errorf("First byte position is negative ('%d')", offsetBegin)
		}
	}

		i2 := <-i2range

		if i2.Name != i1.Name {
			t.Errorf("got ident %s; want %s", i2.Name, i1.Name)
		}

		// here we care about the relative (line-directive adjusted) positions
		l1 := fset.Position(i1.Pos()).Line
		l2 := fset.Position(i2.Pos()).Line
		if l2 != l1 {
			t.Errorf("got line %d; want %d for %s", l2, l1, i1.Name)
		}
	}

	if t.Failed() {
		t.Logf("\n%s", buf.Bytes())
	}
}

}

// seenPos2 tracks whether we have seen a token.Position pair.
var seenPos2 = make(map[pos2]bool)

// dedup takes a token.Position pair and returns a pair that does not
// duplicate any existing pair. The returned pair will have the Offset
// fields cleared.
func dedup(p1, p2 token.Position) (r1, r2 token.Position) {
	key := pos2{
		p1: p1,
		p2: p2,
	}

func ExampleInspect() {
	// src is the input for which we want to inspect the AST.
	src := `
package p
const c = 1.0
var X = f(3.14)*2 + c
`

	// Create the AST by parsing src.
	fset := token.NewFileSet() // positions are relative to fset
	f, err := parser.ParseFile(fset, "src.go", src, 0)
	if err != nil {
		panic(err)
	}

	// Inspect the AST and print all identifiers and literals.
	ast.Inspect(f, func(n ast.Node) bool {