{"KeyValueExpr", `"a"@: b`},

	{"FuncLit", `@func (){}`},
	{"ParenExpr", `@(x)`},
	{"SelectorExpr", `a@.b`},
	{"IndexExpr", `a@[i]`},

	{"SliceExpr", `a@[:]`},
	{"SliceExpr", `a@[i:]`},
	{"SliceExpr", `a@[:j]`},
	{"SliceExpr", `a@[i:j]`},
	{"SliceExpr", `a@[i:j:k]`},

	{"AssertExpr", `x@.(T)`},

	{"Operation", `@*b`},
	{"Operation", `@+b`},
	{"Operation", `@-b`},
	{"Operation", `@!b`},

				continue
			}
			return n.Pos()
		case *KeyValueExpr:
			m = n.Key
		// case *FuncLit:
		// case *ParenExpr:
		case *SelectorExpr:
			m = n.X
		case *IndexExpr:
			m = n.X
		// case *SliceExpr:
		case *AssertExpr:
			m = n.X
		case *TypeSwitchGuard:
			if n.Lhs != nil {
				m = n.Lhs
				continue
			}
			m = n.X
		case *Operation:
			if n.Y != nil {
				m = n.X
				continue
			}

	case *ast.IndexExpr, *ast.IndexListExpr:
		ix := typeparams.UnpackIndexExpr(x)
		WriteExpr(buf, ix.X)
		buf.WriteByte('[')
		writeExprList(buf, ix.Indices)
		buf.WriteByte(']')

	case *ast.SliceExpr:
		WriteExpr(buf, x.X)
		buf.WriteByte('[')
		if x.Low != nil {
			WriteExpr(buf, x.Low)
		}
		buf.WriteByte(':')
		if x.High != nil {
			WriteExpr(buf, x.High)
		}
		if x.Slice3 {

		return 1 << nReturnStmt
	case *ast.SelectStmt:
		return 1 << nSelectStmt
	case *ast.SelectorExpr:
		return 1 << nSelectorExpr
	case *ast.SendStmt:
		return 1 << nSendStmt
	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:

		X       Expr      // expression
		Lbrack  token.Pos // position of "["
		Indices []Expr    // index expressions
		Rbrack  token.Pos // position of "]"
	}

	// A SliceExpr node represents an expression followed by slice indices.
	SliceExpr struct {
		X      Expr      // expression
		Lbrack token.Pos // position of "["
		Low    Expr      // begin of slice range; or nil
		High   Expr      // end of slice range; or nil

	// a valid type.
	if x.typ == nil {
		x.typ = Typ[Invalid]
	}

	check.index(index, length)
	return false
}

func (check *Checker) sliceExpr(x *operand, e *ast.SliceExpr) {
	check.expr(nil, x, e.X)
	if x.mode == invalid {
		check.use(e.Low, e.High, e.Max)
		return
	}

	valid := false
	length := int64(-1) // valid if >= 0

					}
					x = t.Value
					px = &t.Value
				}
				s.simplifyLiteral(typ, eltType, x, px)
			}
			// node was simplified - stop walk (there are no subnodes to simplify)
			return nil
		}

	case *ast.SliceExpr:
		// a slice expression of the form: s[a:len(s)]
		// can be simplified to: s[a:]
		// if s is "simple enough" (for now we only accept identifiers)
		//

	// a valid type.
	if x.typ == nil {
		x.typ = Typ[Invalid]
	}

	check.index(index, length)
	return false
}

func (check *Checker) sliceExpr(x *operand, e *syntax.SliceExpr) {
	check.expr(nil, x, e.X)
	if x.mode == invalid {
		check.use(e.Index[:]...)
		return
	}

	valid := false
	length := int64(-1) // valid if >= 0

		children = append(children,
			tok(n.Select, len("select")))

	case *ast.SelectorExpr:
		// nop

	case *ast.SendStmt:
		children = append(children,
			tok(n.Arrow, len("<-")))

	case *ast.SliceExpr:
		children = append(children,
			tok(n.Lbrack, len("[")),
			tok(n.Rbrack, len("]")))

	case *ast.StarExpr:
		children = append(children, tok(n.Star, len("*")))

	case *ast.StructType:

		w.node(n.Body)

	case *ParenExpr:
		w.node(n.X)

	case *SelectorExpr:
		w.node(n.X)
		w.node(n.Sel)

	case *IndexExpr:
		w.node(n.X)
		w.node(n.Index)

	case *SliceExpr:
		w.node(n.X)
		for _, x := range n.Index {
			if x != nil {
				w.node(x)
			}
		}

	case *AssertExpr:
		w.node(n.X)
		w.node(n.Type)

	case *TypeSwitchGuard: