code: def get(self, server):
          
  
          # Handle indexes
          if isinstance(server, int):
              if server >= len(self.sessions):
                  return None
              else:
                  return self.sessions[server]
  
          # Handle server URLs
          index = self._get_index(server)
          if index == -1:
              return None
          else:
              return self.sessions[index]
docs: Returns a registered GPServer object with a matching GenePattern server url or index
          Returns None if no matching result was found
          :param server:
          :return: