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 has_next_box(self):
      if self.has_length:
          return self.fp.tell() + self.remaining_in_box < self.length
      else:
          return True
  
imports: from __future__ import annotations
  import io
  import os
  import struct
  from .None import Image, ImageFile, _binary
label_desc: Use image node_id 6 for calling the BoxReader obj's underlying member method code with example usage: obj.has_next_box() and returns: unknown, True