case *SelectorExpr:
		Walk(v, n.X)
		Walk(v, n.Sel)

	case *IndexExpr:
		Walk(v, n.X)
		Walk(v, n.Index)

	case *IndexListExpr:
		Walk(v, n.X)
		walkList(v, n.Indices)

	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:

		expr
	}

	// X[Index]
	// X[T1, T2, ...] (with Ti = Index.(*ListExpr).ElemList[i])
	IndexExpr struct {
		X     Expr
		Index Expr
		expr
	}

	// X[Index[0] : Index[1] : Index[2]]
	SliceExpr struct {
		X     Expr
		Index [3]Expr
		// Full indicates whether this is a simple or full slice expression.
		// In a valid AST, this is equivalent to Index[2] != nil.

		f.walk(&n.X, context, visit)
	case *ast.SelectorExpr:
		f.walk(&n.X, ctxSelector, visit)
	case *ast.IndexExpr:
		f.walk(&n.X, ctxExpr, visit)
		f.walk(&n.Index, ctxExpr, visit)
	case *ast.SliceExpr:
		f.walk(&n.X, ctxExpr, visit)
		if n.Low != nil {
			f.walk(&n.Low, ctxExpr, visit)
		}
		if n.High != nil {
			f.walk(&n.High, ctxExpr, visit)
		}
		if n.Max != nil {

	case *ast.IndexExpr:
		a.apply(n, "X", nil, n.X)
		a.apply(n, "Index", nil, n.Index)

	case *ast.IndexListExpr:
		a.apply(n, "X", nil, n.X)
		a.applyList(n, "Indices")

	case *ast.SliceExpr:
		a.apply(n, "X", nil, n.X)
		a.apply(n, "Low", nil, n.Low)
		a.apply(n, "High", nil, n.High)
		a.apply(n, "Max", nil, n.Max)

	case *ast.TypeAssertExpr:
		a.apply(n, "X", nil, n.X)

	case ir.OSTRINGHEADER:
		n := n.(*ir.StringHeaderExpr)
		return walkStringHeader(n, init)

	case ir.OSLICE, ir.OSLICEARR, ir.OSLICESTR, ir.OSLICE3, ir.OSLICE3ARR:
		n := n.(*ir.SliceExpr)
		return walkSlice(n, init)

	case ir.ONEW:
		n := n.(*ir.UnaryExpr)
		return walkNew(n, init)

	case ir.OADDSTR:
		return walkAddString(n.(*ir.AddStringExpr), init)

	case ir.OAPPEND:

			if !enableReverseTypeInference {
				T = nil
			}
			check.funcInst(T, e.Pos(), x, ix, true)
		}
		if x.mode == invalid {
			goto Error
		}

	case *ast.SliceExpr:
		check.sliceExpr(x, e)
		if x.mode == invalid {
			goto Error
		}

	case *ast.TypeAssertExpr:
		check.expr(nil, x, e.X)
		if x.mode == invalid {
			goto Error
		}

		walkBeforeAfter(&n.X, before, after)
		walkBeforeAfter(&n.Index, before, after)
	case *ast.IndexListExpr:
		walkBeforeAfter(&n.X, before, after)
		walkBeforeAfter(&n.Indices, before, after)
	case *ast.SliceExpr:
		walkBeforeAfter(&n.X, before, after)
		if n.Low != nil {
			walkBeforeAfter(&n.Low, before, after)
		}
		if n.High != nil {
			walkBeforeAfter(&n.High, before, after)
		}
	case *ast.TypeAssertExpr:

			if !enableReverseTypeInference {
				T = nil
			}
			check.funcInst(T, e.Pos(), x, e, true)
		}
		if x.mode == invalid {
			goto Error
		}

	case *syntax.SliceExpr:
		check.sliceExpr(x, e)
		if x.mode == invalid {
			goto Error
		}

	case *syntax.AssertExpr:
		check.expr(nil, x, e.X)
		if x.mode == invalid {
			goto Error
		}

				typeof[n] = typeof[n.X]
				return
			}
			// x.(T) has type T.
			if t := typeof[n.Type]; isType(t) {
				typeof[n] = getType(t)
			} else {
				typeof[n] = gofmt(n.Type)
			}

		case *ast.SliceExpr:
			// x[i:j] has type of x.
			typeof[n] = typeof[n.X]

		case *ast.IndexExpr:
			// x[i] has key type of x's type.
			t := expand(typeof[n.X])

		p.print(_Rbrace)

	case *ParenExpr:
		p.print(_Lparen, n.X, _Rparen)

	case *SelectorExpr:
		p.print(n.X, _Dot, n.Sel)

	case *IndexExpr:
		p.print(n.X, _Lbrack, n.Index, _Rbrack)

	case *SliceExpr:
		p.print(n.X, _Lbrack)
		if i := n.Index[0]; i != nil {
			p.printNode(i)
		}
		p.print(_Colon)
		if j := n.Index[1]; j != nil {
			p.printNode(j)
		}
		if k := n.Index[2]; k != nil {