code: async def smove(self, src, dst, value):
          
          res = await self.srem(src, value)
  
          # Only add the element if existed in src set
          if res == 1:
              await self.sadd(dst, value)
  
          return res
docs: Move ``value`` from set ``src`` to set ``dst`` atomically
  
          Cluster impl:
              SMEMBERS --> SREM --> SADD. Function is no longer atomic.