docs: def current_user(self):
          """Returns the username of the current user.
  
          :rtype: str
          """
          if not hasattr(self, '_serverInfo') or 'username' not in self._serverInfo:
  
              url = self._get_url('serverInfo')
              r = self._session.get(url, headers=self._options['headers'])
  
              r_json = json_loads(r)
              if 'x-ausername' in r.headers:
                  r_json['username'] = r.headers['x-ausername']
              else:
                  r_json['username'] = None
              self._serverInfo = r_json
              # del r_json['self']  # this isn't really an addressable resource
          return self._serverInfo['username']