// start position.
	u := unusedInspector{unused: make(map[token.Pos]bool)}
	u.node(file)

	// Then, delete said nodes via astutil.Apply.
	pre := func(c *astutil.Cursor) bool {
		node := c.Node()
		if node == nil {
			return true
		}
		if u.unused[node.Pos()] {
			c.Delete()
			// Unused imports and declarations use exactly
			// one line. Prevent leaving an empty line.

	NodeBool                       // A boolean constant.
	NodeChain                      // A sequence of field accesses.
	NodeCommand                    // An element of a pipeline.
	NodeDot                        // The cursor, dot.
	nodeElse                       // An else action. Not added to tree.
	nodeEnd                        // An end action. Not added to tree.
	NodeField                      // A field or method name.

	})
	type Wndclassex struct {
		Size       uint32
		Style      uint32
		WndProc    uintptr
		ClsExtra   int32
		WndExtra   int32
		Instance   syscall.Handle
		Icon       syscall.Handle
		Cursor     syscall.Handle
		Background syscall.Handle
		MenuName   *uint16
		ClassName  *uint16
		IconSm     syscall.Handle
	}
	name := syscall.StringToUTF16Ptr("test_window")
	wc := Wndclassex{
		WndProc:   cb,