code: def qscan(self, cursor=0, count=None, busyloop=None, minlen=None,
                maxlen=None, importrate=None):
          
          command = ["QSCAN", cursor]
          if count:
              command += ["COUNT", count]
          if busyloop:
              command += ["BUSYLOOP"]
          if minlen:
              command += ["MINLEN", minlen]
          if maxlen:
              command += ["MAXLEN", maxlen]
          if importrate:
              command += ["IMPORTRATE", importrate]
  
          return self.execute_command(*command)
docs: Iterate all the existing queues in the local node.
  
          :param count: An hint about how much work to do per iteration.
          :param busyloop: Block and return all the elements in a busy loop.
          :param minlen: Don't return elements with less than count jobs queued.
          :param maxlen: Don't return elements with more than count jobs queued.
          :param importrate: Only return elements with an job import rate
                          (from other nodes) >= rate.