Extracts the arms of the bandit if any.

def get_bandit(self):
        """
        Extracts the arms of the bandit if any.
        """
        arms_bandit = []
        for d in self.space:
            if d.type == 'bandit':
                arms_bandit += tuple(map(tuple, d.domain))
        return np.asarray(arms_bandit)