code: def del_key(self, ref):
          
          if ref not in self.keys:
              response = self.request("client_del_key %s" % (ref))
              self.keys.remove(ref)
              if "success" in response:
                  return None
              else:
                  return response
docs: Delete a key.
  
          (ref)
          Return None or LCDd response on error