code: def _set_file_encoding_utf8(filename):
      
      with open(filename, 'r+') as f:
          content = f.read()
          f.seek(0, 0)
          f.write("# -*- coding: utf-8 -*-\n" + content)
docs: set a encoding header as suggested in PEP-0263. This
      is not entirely correct because we don't know the encoding of the
      given file but it's at least a chance to get metadata from the setup.py