class_docstr: A small helper class to read fields stored in JPEG2000 header boxes
  and to easily step into and read sub-boxes.
code: def read_boxes(self):
      size = self.remaining_in_box
      data = self._read_bytes(size)
      return BoxReader(io.BytesIO(data), size)
  
imports: from __future__ import annotations
  import io
  import os
  import struct
  from .None import Image, ImageFile, _binary
label_desc: Use image node_id 5 for calling the BoxReader obj's underlying member method code with example usage: obj.read_boxes() and returns: BoxReader