Make wrapper only snatch every 4th grading work

wrapper.py

@@ -13,6 +13,8 @@ development_mode = os.getenv('PYCHARM_HOSTED')
 def main():
     log = logging.getLogger('wrapper')
 
+    messages_seen = []
+
     log.info("Running main")
     host = 'localhost' if development_mode else 'redis.wendt.vpn'
     try:
@@ -40,8 +42,15 @@ def main():
                                 subject = data["headers"]["subject"]
                                 log.info(f"Subject: {subject}")
                                 if "III Grading Required" in subject:
+                                    if len(messages_seen) == 0:
                                         log.info("Subject found - let's go snatching!")
                                         snatch_grading_work()
+                                    else:
+                                        log.info("Not snatching this one, only every 4th")
+                                        messages_seen.append(message)
+                                        if len(messages_seen) == 4:
+                                            log.info("Clearing message log, snatching the next one")
+                                            messages_seen = []
                                 else:
                                     log.info("Ignoring this email")
             except Exception as e: