func (check *Checker) binary(x *operand, e syntax.Expr, lhs, rhs syntax.Expr, op syntax.Operator) {
	var y operand

	check.expr(nil, x, lhs)
	check.expr(nil, &y, rhs)

	if x.mode == invalid {
		return
	}
	if y.mode == invalid {
		x.mode = invalid
		x.expr = y.expr
		return
	}

	if isShift(op) {
		check.shift(x, &y, e, op)
		return
	}

func (check *Checker) binary(x *operand, e ast.Expr, lhs, rhs ast.Expr, op token.Token, opPos token.Pos) {
	var y operand

	check.expr(nil, x, lhs)
	check.expr(nil, &y, rhs)

	if x.mode == invalid {
		return
	}
	if y.mode == invalid {
		x.mode = invalid
		x.expr = y.expr
		return
	}

	if isShift(op) {
		check.shift(x, &y, e, op)
		return
	}

	var inst *syntax.IndexExpr // function instantiation, if any
	if iexpr, _ := call.Fun.(*syntax.IndexExpr); iexpr != nil {
		if check.indexExpr(x, iexpr) {
			// Delay function instantiation to argument checking,
			// where we combine type and value arguments for type
			// inference.
			assert(x.mode == value)
			inst = iexpr
		}
		x.expr = iexpr
		check.record(x)
	} else {
		check.exprOrType(x, call.Fun, true)

func (p *parser) pexpr(x Expr, keep_parens bool) Expr {
	if trace {
		defer p.trace("pexpr")()
	}

	if x == nil {
		x = p.operand(keep_parens)
	}

loop:
	for {
		pos := p.pos()
		switch p.tok {
		case _Dot:
			p.next()
			switch p.tok {
			case _Name:
				// pexpr '.' sym
				t := new(SelectorExpr)
				t.pos = pos

	case *types.Struct:
		texpr := TypeExpr(f, pkg, typ) // typ because we want the name here.
		if texpr == nil {
			return nil
		}
		return &ast.CompositeLit{
			Type: texpr,
		}
	}
	return nil
}

// IsZeroValue checks whether the given expression is a 'zero value' (as determined by output of
// analysisinternal.ZeroValue)
func IsZeroValue(expr ast.Expr) bool {
	switch e := expr.(type) {

	for {
		// check if we have a pointer type
		// if pexpr, _ := typ.(*ast.StarExpr); pexpr != nil {
		if pexpr, _ := typ.(*syntax.Operation); pexpr != nil && pexpr.Op == syntax.Mul && pexpr.Y == nil {
			// if we've already seen a pointer, we're done
			if ptr {
				return false, nil
			}
			ptr = true
			typ = syntax.Unparen(pexpr.X) // continue with pointer base type
		}

		// var decl w/o init expr
		if s.Type == nil {
			check.error(s, code, "missing type or init expr")
		}
	case l < r:
		if l < len(s.Values) {
			// init exprs from s
			n := s.Values[l]
			check.errorf(n, code, "extra init expr %s", n)
			// TODO(gri) avoid declared and not used error here
		} else {
			// init exprs "inherited"
			check.errorf(s, code, "extra init expr at %s", check.fset.Position(init.Pos()))

}  // namespace tensorflow

#define TF_STATUS_ASSIGN_OR_RETURN(lhs, rexpr, c_status) \
  _TF_STATUS_ASSIGN_OR_RETURN_IMPL(                      \
      _TF_STATUS_CONCAT(_status_or_value, __COUNTER__), lhs, rexpr, c_status);

#define _TF_STATUS_ASSIGN_OR_RETURN_IMPL(statusor, lhs, rexpr, c_status) \
  auto statusor = (rexpr);                                               \

			expr:        `isQuantity("20Mi")`,
			expectValue: trueVal,
		},
		{
			name:        "isQuantity_invalidSuffix",
			expr:        `isQuantity("20Mo")`,
			expectValue: falseVal,
		},
		{
			name:        "isQuantity_passingRegex",
			expr:        `isQuantity("10Mm")`,
			expectValue: falseVal,
		},
		{
			name:               "isQuantity_noOverload",

			expr:               "'abc 123 def 123'.replace('123', '456', 1)",
			expectEsimatedCost: checker.CostEstimate{Min: 3, Max: 3},
			expectRuntimeCost:  3,
		},
		{
			name:               "split",
			expr:               "'abc 123 def 123'.split(' ')",
			expectEsimatedCost: checker.CostEstimate{Min: 3, Max: 3},
			expectRuntimeCost:  3,
		},
		{
			name:               "split with limit",