code: def _process_config(self):
          
          self._user_agent_adding_config = botocore.config.Config(user_agent_extra=USER_AGENT_SUFFIX)
  
          if self.config.region_names:
              self.add_regional_clients_from_list(self.config.region_names)
              self.default_region = self.config.region_names[0]
          else:
              self.default_region = self.config.botocore_session.get_config_variable("region")
              if self.default_region is not None:
                  self.add_regional_client(self.default_region)
  
          if self.config.key_ids:
              self.add_master_keys_from_list(self.config.key_ids)
docs: Traverses the config and adds master keys and regional clients as needed.