docs: def __body_format(self, body):
          """
          format body into different type
          :param body:
          :return:
          """
  
          ctype, pdict = parse_header(self.content_type)
          if ctype == 'application/json':
              self.form = json.loads(body.decode())
  
          elif ctype == 'application/x-www-form-urlencoded':
              for key, value in parse_qs(body).items():
                      self.form[key.decode()] = [one_value.decode() for one_value in value]
  
          elif ctype == "multipart/form-data":
              safe_env = {
                  'QUERY_STRING': '',
                  'REQUEST_METHOD': self.method.upper(),
                  'CONTENT_TYPE': self.content_type,
                  'CONTENT_LENGTH': self.headers.get('Content-Length', '-1')
              }
              fields = FieldStorage(io.BytesIO(body), environ=safe_env, keep_blank_values=True)
  
              fields = fields.list or []
              for field in fields:
                  if field.filename:
                      self.form[field.name] = File(field.filename, field.file)
                  else:
                      self.form[field.name] = field.value