code: public void delete(Key key) {
      // This is probably a serious overestimation, but I can't see a good
      // way to find the size in the public API.
      int bytesHere = KeyFactory.keyToString(key).length();
  
      // Do this before the add so that we guarantee that size is never > sizeLimit
      if (deletesBytes + bytesHere >= params.getBytesLimit()) {
        flushDeletes();
      }
  
      deletesBytes += bytesHere;
      deletes.add(key);
  
      if (deletes.size() >= params.getCountLimit()) {
        flushDeletes();
      }
    }
docs: Adds a mutation to put the given entity to the datastore.