code: def fill_width(bytes_, width):
      
  
      while len(bytes_) < width:
          bytes_ = b'\x00' + bytes_
      return bytes_
docs: Ensure a byte string representing a positive integer is a specific width
      (in bytes)
  
      :param bytes_:
          The integer byte string
  
      :param width:
          The desired width as an integer
  
      :return:
          A byte string of the width specified