'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):

    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
