code: def file_type(filename, param='rb'):
      
      magic_dict = {
          b"\x1f\x8b\x08": "gz",
          b"\x42\x5a\x68": "bz2",
          b"\x50\x4b\x03\x04": "zip"
      }
      if param.startswith('w'):
          return filename.split('.')[-1]
      max_len = max(len(x) for x in magic_dict)
      with open(filename, 'rb') as f:
          file_start = f.read(max_len)
      for magic, filetype in list(magic_dict.items()):
          if file_start.startswith(magic):
              return filetype
      return "no match"
docs: returns the type of file, e.g., gz, bz2, normal