docs: def create_token(self, user_id, permission_obj):
          """ 'permission_obj' param should be a string. 
                  e.g. '[{"access":"d_u_list","oid":{"id":"1576946496","type":"Domain"}}]'
  
          http://docs.exosite.com/portals/#add-user-permission
          """
  
          headers = {
                  'User-Agent': self.user_agent(),
                  'Content-Type': self.content_type()
          }
          headers.update(self.headers())
  
          url = self.portals_url()+'/users/{0}/permissions'.format(user_id)
          # print("URL: {0}".format(url))
          r = requests.post(  url,
                              data=permission_obj,
                              headers=headers,
                              auth=self.auth())
      
          if HTTP_STATUS.OK == r.status_code:
              return r.json()
          else:
              print("create_token: Something went wrong: <{0}>: {1}".format(
                          r.status_code, r.reason))
              r.raise_for_status()