A line such as yield item produces a value that is received by the caller of next(...), and it also gives way, suspending the execution of the generator so that the caller may proceed until it‘s ready to consume another value by invkoing next() again. The caller pulls values from the generator.
A coroutine is syntactically like a generator: just a function with the yield keyword in its body. However, in a coroutine, yield usually appears on the right side of an expression (e.g., datum = yield), and it may or may not produce a value -- if there is no expression after the yield keyword, the generator yields None. The coroutine may receive data from the caller, which uses .send(datum) instead of next(...) to feed the coroutine. Usually, the caller pushes values into the coroutine.
end...
原文：https://www.cnblogs.com/neozheng/p/12460073.html