code: def _rc_brpoplpush(self, src, dst, timeout=0):
          
          rpop = self.brpop(src, timeout)
          if rpop is not None:
              self.lpush(dst, rpop[1])
              return rpop[1]
          return None
docs: Pop a value off the tail of ``src``, push it on the head of ``dst``
          and then return it.
  
          This command blocks until a value is in ``src`` or until ``timeout``
          seconds elapse, whichever is first. A ``timeout`` value of 0 blocks
          forever.
          Not atomic