def update_user(self, user_id,
                    roles=None, netmask=None,
                    secret=None, pubkey=None):
        """Update user. Returns the raw response object.

        Arguments:
            user_id:
                User id of user to update
            roles:
                Role
            netmask:
                Limit user connections by netmask, for example 192.168.1.0/24
            secret:
                Secret used when authenticating with mCASH
            pubkey:
                RSA key used for authenticating by signing
        """
        arguments = {'roles': roles,
                     'netmask': netmask,
                     'secret': secret,
                     'pubkey': pubkey}
        return self.do_req('PUT',
                           self.merchant_api_base_url + '/user/' +
                           user_id + '/', arguments)