code: def parse(cls, fptr, offset, length):
          
          box = cls(length=length, offset=offset)
  
          # The JP2 header box is a superbox, so go ahead and parse its child
          # boxes.
          box.box = box.parse_superbox(fptr)
  
          return box
docs: Parse JPEG 2000 header box.
  
          Parameters
          ----------
          fptr : file
              Open file object.
          offset : int
              Start position of box in bytes.
          length : int
              Length of the box in bytes.
  
          Returns
          -------
          JP2HeaderBox
              Instance of the current JP2 header box.