Created by: zeffii
i don't know if this is needed, or if it's just extra complexity.
it's a decorator for the node's update function. For most nodes we don't need to implement the update function, only for nodes which change their ui according to user interaction with sockets.
When we do implement the update function, we have a few checks at the top of the function that must be done before any real dynamic UI code can be run.
Usually the code in the update function consists out of testing to see if the last output was generated, and perhaps if certain sockets are connected. The example i'll use is the combinatorics node This PR contains the poll_node decorator, which wraps the update function, the decorator will call a function called "sv_poll", which will return true is you want to avoid calling update. (in that sense it is in reverse to to normal operator poll)