Following the polymorphic inheritance setup given by sqlalchemy docs here, how do I add a query function to the company table that returns its managers’ names?

It would look something like this, but I cannot figure out how to make it work

from sqlalchemy.orm import selectin_polymorphic

class Company(Base):
    (...)

    def manager_names(self):
        # this doesn't work
        loader_opt = selectin_polymorphic(Employee, [Manager])
        return [i.name for i in self.employee.options(loader_opt).all()]

Here is the relevant part of the setup (copied from the link above):

from sqlalchemy import create_engine
from sqlalchemy import ForeignKey
from sqlalchemy.orm import DeclarativeBase
from sqlalchemy.orm import Mapped
from sqlalchemy.orm import mapped_column
from sqlalchemy.orm import relationship
from sqlalchemy.orm import Session

class Base(DeclarativeBase):
    pass
class Company(Base):
    __tablename__ = "company"
    id: Mapped[int] = mapped_column(primary_key=True)
    name: Mapped[str]
    employees: Mapped[List["Employee"]] = relationship(back_populates="company")

class Employee(Base):
    __tablename__ = "employee"
    id: Mapped[int] = mapped_column(primary_key=True)
    name: Mapped[str]
    type: Mapped[str]
    company_id: Mapped[int] = mapped_column(ForeignKey("company.id"))
    company: Mapped[Company] = relationship(back_populates="employees")
    def __repr__(self):
        return f"{self.__class__.__name__}({self.name!r})"
    __mapper_args__ = {
        "polymorphic_identity": "employee",
        "polymorphic_on": "type",
    }

class Manager(Employee):
    __tablename__ = "manager"
    id: Mapped[int] = mapped_column(ForeignKey("employee.id"), primary_key=True)
    manager_name: Mapped[str]
    __mapper_args__ = {
        "polymorphic_identity": "manager",
    }