code: def f2format(filename):
      
      print('Now converting %r...' % filename)
  
      # fetch encoding
      encoding = os.getenv('F2FORMAT_ENCODING', LOCALE_ENCODING)
  
      lineno = dict()     # line number -> file offset
      content = list()    # file content
      with open(filename, 'r', encoding=encoding) as file:
          lineno[1] = 0
          for lnum, line in enumerate(file, start=1):
              content.append(line)
              lineno[lnum+1] = lineno[lnum] + len(line)
  
      # now, do the dirty works
      string = ''.join(content)
      text = convert(string, lineno)
  
      # dump back to the file
      with open(filename, 'w', encoding=encoding) as file:
          file.write(text)
docs: Wrapper works for conversion.
  
      Args:
       - filename -- str, file to be converted