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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _update_user_roles_names_from_roles_id(self, user, users_roles, roles_list):
 """Add roles names to user.roles, based on users_roles. :param user: user to update :param users_roles: list of roles ID :param roles_list: list of roles obtained with keystone """

        user_roles_names = [role.name for role in roles_list
                            if role.id in users_roles]
        current_user_roles_names = set(getattr(user, "roles", []))
        user.roles = list(current_user_roles_names.union(user_roles_names))