I just tried one in Firefox 17, and you can prime it by calling send() with no argument. It objects if there is an argument on the initial send().
send() is equivalent to send(undefined) which is equivalent to next().
This equivalence is true in Python as well, but you have to explicitly call send(None) which is annoying.
I just tried one in Firefox 17, and you can prime it by calling send() with no argument. It objects if there is an argument on the initial send().