System.Linq.Expressions.Expression.GetMethodBasedAssignOperator C# (CSharp) Method

        private static BinaryExpression GetMethodBasedAssignOperator(ExpressionType binaryType, Expression left, Expression right, MethodInfo method, LambdaExpression conversion, bool liftToNull)
        {
            BinaryExpression b = GetMethodBasedBinaryOperator(binaryType, left, right, method, liftToNull);
            if (conversion == null)
            {
                // return type must be assignable back to the left type
                if (!TypeUtils.AreReferenceAssignable(left.Type, b.Type))
                {
                    throw Error.UserDefinedOpMustHaveValidReturnType(binaryType, b.Method.Name);
                }
            }
            else
            {
                // add the conversion to the result
                ValidateOpAssignConversionLambda(conversion, b.Left, b.Method, b.NodeType);
                b = new OpAssignMethodConversionBinaryExpression(b.NodeType, b.Left, b.Right, b.Left.Type, b.Method, conversion);
            }
            return b;
        }