code: def _n(v):
          
          if v is None:
              return ""
  
          if isinstance(v, (dict, list)):
              try:
                  v = json.dumps(v)
              except Exception:
                  pass
          elif six.PY2 and isinstance(v, six.text_type):
              v = v.encode('utf8', "ignore")
          elif six.PY3 and isinstance(v, six.binary_type):
              v = v.decode('utf8', "ignore")
  
          return str(v)
docs: convert string to utf8 in Py2 or unicode in Py3
          :param v:
          :return: