Simple example of using python coroutines and generators to create a market simulator with:

1) A one-good market, collecting bids from the agents, which, after each trading period, updates each price, and

2) a set of agents, observing the market price at each trading period, and submitting bids back.

Such a setup would usually be achieved by the observer pattern, where each trader will subscribe to the price changes, but usage of generators and coroutines leads to more elegant code in this case.