code: async def add(self, setname, ip, timeout=0):
          
          args = ['add', '-exist', setname, ip, 'timeout', timeout]
  
          return await self.start(__class__.CMD, *args)
docs: Adds the given IP address to the given ipset.
          
          If a timeout is given, the IP will stay in the ipset for
          the given duration. Else it's added forever.
  
          The resulting command looks like this:
  
          ``ipset add -exist ellis_blacklist4 192.0.2.10 timeout 14400``