code: func isWrite(op api.KVOp) bool {
  	switch op {
  	case api.KVSet, api.KVDelete, api.KVDeleteCAS, api.KVDeleteTree, api.KVCAS, api.KVLock, api.KVUnlock:
  		return true
  	}
  	return false
  }
docs: // isWrite returns true if the given operation alters the state store.