async readBlockData(blockNumber, zd) {

        const idx = await zd.blockIndex.getBlockIndexEntry(blockNumber);

        if (!idx) {
            return undefined
        } else {

            return this.file.read(idx.filePosition, idx.size)
        }
    }
/***
     * Return the raw data for the block.  Function provided for testing and development
     * @param blockNumber
     * @param zd
     * @returns {Promise<void>}
     */
Return the raw data for the block.  Function provided for testing and development
@param blockNumber
@param zd
@returns {Promise}
Return the raw data for the block . Function provided for testing and development @param blockNumber @param zd @returns { Promise }
async readBlockData(blockNumber, zd) {
        const idx = await zd.blockIndex.getBlockIndexEntry(blockNumber);
        if (!idx) {
            return undefined
        } else {
            return this.file.read(idx.filePosition, idx.size)
        }
    }
async readBlockData ( blockNumber , zd ) { const idx = await zd . blockIndex . getBlockIndexEntry ( blockNumber ) ; if ( ! idx ) { return undefined } else { return this . file . read ( idx . filePosition , idx . size ) } }
Return the raw data for the block.
Return the raw data for the block .