class_docstr: A small helper class to read fields stored in JPEG2000 header boxes
  and to easily step into and read sub-boxes.
class_docstr_tok: ["A","small","helper","class","to","read","fields","stored","in","JPEG2000","header","boxes","and","to","easily","step","into","and","read","sub-boxes","."]
code: def _can_read(self, num_bytes):
      if self.has_length and self.fp.tell() + num_bytes > self.length:
          # Outside box: ensure we don't read past the known file length
          return False
      if self.remaining_in_box >= 0:
          # Inside box contents: ensure read does not go past box boundaries
          return num_bytes <= self.remaining_in_box
      else:
          return True
  
imports: import io
  import os
  import struct
  from .None import Image, ImageFile, _binary
label_desc: Use image node_id 2 for calling the BoxReader obj's underlying member method code with example usage: obj._can_read(num_bytes) and returns: False, unknown, True