Activates a new registree on the LEX with given activation key
        :rtype: None

def activate(self, key):
        """
        Activates a new registree on the LEX with given activation key
        :rtype: None
        """
        url = self._base + 'user/activate'
        r = requests.get(url, params={
            'activation_key': key
        })
        r.raise_for_status()