code: public WrappedByteBuffer putLongAt(int index, long v) {
          _checkForWriteAt(index, 8);
          _buf.putLong(index, v);
          return this;
      }
docs: Puts an eight-byte long into the buffer at the specified index.
  
  @param index the index
  @param v the eight-byte long
  
  @return the buffer