code: def unblock_username(username, pipe=None):
      
      do_commit = False
      if not pipe:
          pipe = REDIS_SERVER.pipeline()
          do_commit = True
      if username:
          pipe.delete(get_username_attempt_cache_key(username))
          pipe.delete(get_username_blocked_cache_key(username))
          if do_commit:
              pipe.execute()
docs: unblock the given Username