code: def read_file(self, filename):
          
          self.pack = {}
          with open(filename, "r") as f:
              for line in f:
                  line = line.strip()
                  if (len(line) == 0) or (line[0] == "#"):
                      continue
                  try:
                      self._parse_modulus(line)
                  except:
                      continue
docs: :raises IOError: passed from any file operations that fail.