Removes a role from a user.

        :param user: The user to manipulate
        :param role: The role to remove from the user

def remove_role_from_user(self, user, role):
        """Removes a role from a user.

        :param user: The user to manipulate
        :param role: The role to remove from the user
        """
        rv = False
        user, role = self._prepare_role_modify_args(user, role)
        if role in user.roles:
            rv = True
            user.roles.remove(role)
            self.put(user)
        return rv