code: def _num_bytes_to_human_readable(num_bytes):
    
    if num_bytes < (2 ** 10):
      return "%d B" % num_bytes
    elif num_bytes < (2 ** 20):
      return "%.3f KB" % (float(num_bytes) / (2 ** 10))
    elif num_bytes < (2 ** 30):
      return "%.3f MB" % (float(num_bytes) / (2 ** 20))
    else:
      return "%.3f GB" % (float(num_bytes) / (2 ** 30))
docs: Returns human readable string of how much memory `num_bytes` fills.