code: protected int readVersion(ReadableByteChannel channel) throws IOException {
          ByteBuffer version = ByteBuffer.allocate(STORAGE_VERSION_LENGTH);
          int len = channel.read(version);
          if (len < STORAGE_VERSION_LENGTH) {
              throw new IOException("Invalid Version");
          }
          return version.getInt(0);
      }
docs: Reads version from readable channel.
  
  @throws IOException