System.Dynamic.DynamicObject.MetaDynamic.CallMethodReturnLast C# (CSharp) Method

            private DynamicMetaObject CallMethodReturnLast(string methodName, DynamicMetaObjectBinder binder, Expression[] args, Expression value, Fallback fallback) {
                //
                // First, call fallback to do default binding
                // This produces either an error or a call to a .NET member
                //
                DynamicMetaObject fallbackResult = fallback(null);

                //
                // Build a new expression like:
                // {
                //   object result;
                //   TrySetMember(payload, result = value) ? result : fallbackResult
                // }
                //

                var result = Expression.Parameter(typeof(object), null);
                var callArgs = Expression.Parameter(typeof(object[]), null);
                var callArgsValue = GetConvertedArgs(args);

                var callDynamic = new DynamicMetaObject(
                    Expression.Block(
                        new[] { result, callArgs },
                        Expression.Assign(callArgs, Expression.NewArrayInit(typeof(object), callArgsValue)),
                        Expression.Condition(
                            Expression.Call(
                                GetLimitedSelf(),
                                typeof(DynamicObject).GetMethod(methodName),
                                BuildCallArgs(
                                    binder,
                                    args,
                                    callArgs,
                                    Expression.Assign(result, Expression.Convert(value, typeof(object)))
                                )
                            ),
                            Expression.Block(
                                ReferenceArgAssign(callArgs, args),
                                result
                            ),
                            fallbackResult.Expression,
                            typeof(object)
                        )
                    ),
                    GetRestrictions().Merge(fallbackResult.Restrictions)
                );

                //
                // Now, call fallback again using our new MO as the error
                // When we do this, one of two things can happen:
                //   1. Binding will succeed, and it will ignore our call to
                //      the dynamic method, OR
                //   2. Binding will fail, and it will use the MO we created
                //      above.
                //
                return fallback(callDynamic);
            }