Problem: John Maynard Keynes (1883-1946) has opened a new chapter of economics by creating several fundamentals to modern macroeconomics. Keynesian economics argues that effective demand is crucial. The driving force of an economy is aggregate demand-the total spending for goods and services by the private sector and government. In this model, total spending determines all economic outcomes, from total production to employment rate. The Keynesian solution to lack of demand and the adverse effects of economic downturn by using fiscal and monetary stimulus has become the mainstream economic policies after the WWII. Use one example to explain how fiscal and monetary policies work in the real world. (Your answer is about 400 words.)