nodeFilter := []ast.Node{
		(*ast.TypeAssertExpr)(nil),
		(*ast.TypeSwitchStmt)(nil),
	}
	var free typeparams.Free
	inspect.Preorder(nodeFilter, func(n ast.Node) {
		var (
			assert  *ast.TypeAssertExpr // v.(T) expression
			targets []ast.Expr          // interfaces T in v.(T)
		)
		switch n := n.(type) {
		case *ast.TypeAssertExpr:
			// take care of v.(type) in *ast.TypeSwitchStmt

		if x.High != nil {
			WriteExpr(buf, x.High)
		}
		if x.Slice3 {
			buf.WriteByte(':')
			if x.Max != nil {
				WriteExpr(buf, x.Max)
			}
		}
		buf.WriteByte(']')

	case *ast.TypeAssertExpr:
		WriteExpr(buf, x.X)
		buf.WriteString(".(")
		WriteExpr(buf, x.Type)
		buf.WriteByte(')')

	case *ast.CallExpr:
		WriteExpr(buf, x.Fun)
		buf.WriteByte('(')
		writeExprList(buf, x.Args)

	case *ast.SliceExpr:
		return 1 << nSliceExpr
	case *ast.StarExpr:
		return 1 << nStarExpr
	case *ast.StructType:
		return 1 << nStructType
	case *ast.SwitchStmt:
		return 1 << nSwitchStmt
	case *ast.TypeAssertExpr:
		return 1 << nTypeAssertExpr
	case *ast.TypeSpec:
		return 1 << nTypeSpec
	case *ast.TypeSwitchStmt:
		return 1 << nTypeSwitchStmt
	case *ast.UnaryExpr:
		return 1 << nUnaryExpr
	case *ast.ValueSpec:

	case *SliceExpr:
		Walk(v, n.X)
		if n.Low != nil {
			Walk(v, n.Low)
		}
		if n.High != nil {
			Walk(v, n.High)
		}
		if n.Max != nil {
			Walk(v, n.Max)
		}

	case *TypeAssertExpr:
		Walk(v, n.X)
		if n.Type != nil {
			Walk(v, n.Type)
		}

	case *CallExpr:
		Walk(v, n.Fun)
		walkList(v, n.Args)

	case *StarExpr:
		Walk(v, n.X)

	case *UnaryExpr: