How to use the graphene-sqlalchemy.examples.flask_sqlalchemy.schema.Employee function in graphene-sqlalchemy

class Meta:
        model = EmployeeModel
        interfaces = (relay.Node, )


class Role(SQLAlchemyObjectType):

    class Meta:
        model = RoleModel
        interfaces = (relay.Node, )


class Query(graphene.ObjectType):
    node = relay.Node.Field()
    all_employees = SQLAlchemyConnectionField(Employee)
    all_roles = SQLAlchemyConnectionField(Role)
    role = graphene.Field(Role)


schema = graphene.Schema(query=Query, types=[Department, Employee, Role])