Catyre's Code

        _timeToFirstFrame = win.getFutureFlipTime(clock="now")
        trialClock.reset(-_timeToFirstFrame) # t0 is time of first possible fli

        streams = reposition(streams, level)  # Reposition each stimuli to the correct place

        # Iterate over the letters in each stream and display them appropriately
        for letters, T_nearby in trial.stream:
            # get current time
            tThisFlip = win.getFutureFlipTime(clock=trialClock)
            tThisFlipGlobal = win.getFutureFlipTime(clock=None)

            # Check if there is a target in the stream
            T_in_stream = "T" in letters

            if heads_up.status == NOT_STARTED and tThisFlip >= 0.0 - frame_tolerance:
                heads_up.status = STARTED
                heads_up.tStartRefresh = tThisFlipGlobal
                heads_up.tStopRefresh = FOREVER # Arbitrary large number, will be adjusted when the conditions are met
                win.timeOnFlip(heads_up, "tStartRefresh")
                heads_up.setAutoDraw(True)
            if heads_up.status == STARTED:
                if tThisFlipGlobal > heads_up.tStartRefresh + 1 - frame_tolerance:
                    heads_up.status = FINISHED
                    heads_up.tStopRefresh = tThisFlipGlobal
                    win.timeOnFlip(heads_up, "tStopRefresh")
                    heads_up.setAutoDraw(False)

            # Display fixation
            if fixation.status == NOT_STARTED and trial.rsvp_stream_count > 1 and tThisFlipGlobal >= heads_up.tStopRefresh - frame_tolerance:
                fixation.status = STARTED
                fixation.tStartRefresh = tThisFlipGlobal
                fixation.setAutoDraw(True)
                win.timeOnFlip(fixation, "tStartRefresh")
            if fixation.status == STARTED:
                if tThisFlipGlobal > fixation.tStartRefresh + 100 - frame_tolerance:
                    fixation.status = FINISHED
                    win.timeOnFlip(fixation, "tStopRefresh")
                    fixation.setAutoDraw(False)

            # Take every letter and assign it to a stimuli in streams.  Then display the stimulus
            for j in range(len(letters)):
                # Take the jth stream and assign the jth letter to it
                stream = streams[j]
                stream.text = letters[j]

                if stream.status == NOT_STARTED and tThisFlip >= heads_up.tStopRefresh - frame_tolerance:
                    stream.status = STARTED
                    stream.tStartRefresh = tThisFlipGlobal
                    win.timeOnFlip(stream, "tStartRefresh")
                    stream.setAutoDraw(True)
                if stream.status == STARTED:
                    if tThisFlipGlobal > stream.tStartRefresh + 0.4 - frame_tolerance: # 24 frames = 400 ms
                        stream.status = FINISHED
                        win.timeOnFlip(stream, "tStopRefresh")
                        stream.setAutoDraw(False)

            if continueRoutine:
                #core.wait(0.4)
                win.flip()

        # Reset stream statuses to NOT_STARTED so they will still display on the next run-through
        for stream in streams:
            if hasattr(stream, 'status'):
                stream.status = NOT_STARTED