code: def set_shared_config(cls, config):
          
          assert isinstance(config, dict)
          cls._sharedInstance.config.update(config)
          # if one is already set, delete
          if cls._sharedInstance.instance:
              cls._sharedInstance.instance = None
docs: This allows to set a config that will be used when calling
              ``shared_blockchain_instance`` and allows to define the configuration
              without requiring to actually create an instance