constructor(props, context) {
    super(props, context);

    this._cellMetadata = [];
    this._lastRenderedCellIndices = [];

    // Cell cache during scroll (for performance)
    this._cellCache = [];

    this._isScrollingChange = this._isScrollingChange.bind(this);
    this._setCollectionViewRef = this._setCollectionViewRef.bind(this);
  }
Optionally override the size of the sections a Collection's cells are split into.