code: def verify_captcha(code, token):
      
      params = {
          'captcha_token': token,
          'captcha_code': code,
      }
      response = leancloud.client.post('/verifyCaptcha', params)
      return response.json()['validate_token']
docs: 验证用户输入与图形验证码是否匹配
      :params code: 用户填写的验证码
      :params token: 图形验证码对应的 token
      :return: validate token