Returns the username of the current user.

        :rtype: str

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']