code: def _parse_ppm_segment(self, fptr):
          
          offset = fptr.tell() - 2
  
          read_buffer = fptr.read(3)
          length, zppm = struct.unpack('>HB', read_buffer)
  
          numbytes = length - 3
          read_buffer = fptr.read(numbytes)
  
          return PPMsegment(zppm, read_buffer, length, offset)
docs: Parse the PPM segment.
  
          Parameters
          ----------
          fptr : file
              Open file object.
  
          Returns
          -------
          PPMSegment
              The current PPM segment.