Python 3: send method of generators

Question

I can\'t understand the send method. I understand that it is used to operate the generator. But the syntax is here: generator.send(value).

Answer 1

The most confusing part should be this line X = yield i, specially when you call send() on the generator. Actually the only thing you need to know is:

in the lexical level: next() is equal to send(None)

in the interpreter level: X = yield i equals to below lines(ORDER MATTERS):

yield i
# won't continue until next() or send() is called
# and this is also the entry point of next() or send()
X = the_input_of_send

and, the 2 lines of comment is the exact reason, why we need to call send(None) for the first time, because the generator will return i (yield i) before assign the value to X