get() -> {'id': 32-byte-md5, 'body': msg-body}

def get(self, timeout=10):
        """get() -> {'id': 32-byte-md5, 'body': msg-body}"""
        req = self.req({'op': 'GET', 'timeout': timeout})
        if req.status_code != 200:
            return None
        result = req.json()
        if result.get('status') != 'ok':
            return False
        return result