code: def open_file(filename, mode='rb'):
      
      if (('r' not in mode or hasattr(filename, 'read')) and
          (('a' not in mode and 'w' not in mode) or hasattr(filename, 'write')) and
          hasattr(filename, '__iter__')):
          return filename
      elif isinstance(filename, string_type):
          if filename == '-' and 'r' in mode:
              if PY3:
                  return sys.stdin.buffer
              return sys.stdin
          elif filename == '-' and ('w' in mode or 'a' in mode):
              if PY3:
                  return sys.stdout.buffer
              return sys.stdout
          if filename.lower().count('.zip:'):
              assert 'r' in mode
              assert filename.count(':') == 1
              import zipfile
              zipped_file = zipfile.ZipFile(filename.split(':')[0])
              unzipped_file = zipped_file.open(filename.split(':')[1], 'r')
              zipped_file.close()
              return unzipped_file
          elif filename.lower().endswith('.gz'):
              import gzip
              return gzip.open(filename, mode)
          elif filename.lower().endswith('.xz'):
              import lzma
              tmp = lzma.LZMAFile(filename, mode)
              dir(tmp)
              return tmp
          else:
              return open(filename, mode)
      else:
          raise Exception('Unknown type for argument filename')
docs: Opens a file for access with the given mode.  This function
      transparently wraps gzip and xz files as well as normal files.
      You can also open zip files using syntax like:
  
      f = utils.open_file('../semcor-parsed.zip:semcor000.txt')