Why does SQLAlchemy return TypeError: object.__init__() takes exactly one argument (the instance to initialize) when I have included the argument?

Here's my code I'm bulding a database model with flask-sqlalchemy. When doing my inheritances, I used super()__init__(cdata) but python returns an error saying it takes exactly one argument.

Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "/mnt/d/September/bank/app/backoffice/models.py", line 31, in __init__
    super().__init__(cdata)
TypeError: object.__init__() takes exactly one argument (the instance to initialize)

Here's my code

from app import db

class Customer(db.Model):
    __tablename__ = "customer"
    id = db.Column(db.Integer, primary_key=True)
    fname = db.Column(db.String(32), nullable=False)
    lname = db.Column(db.String(32), nullable=False)
    customer_type = db.Column(db.String(32))

    __mapper_args__ = {
        "polymorphic_identity": "customer",
        "polymorphic_on": customer_type
    }

    def __init__(self, **cdata):
        self.fname = cdata["fname"]
        self.lname = cdata["lname"]

    def __repr__(self):
        return f"[Customer: {self.fname}]"

class Employee():
    __tablename__ = "employee"
    id = db.Column(db.Integer, db.ForeignKey("customer.id"), primary_key=True)
    title = db.Column(db.String(32), nullable=False)
    __mapper_args = {
        "polymorphic_identity": "employee"
    }

    def __init__(self, cdata):
        super().__init__(cdata)

Where could I have gone wrong> I have given the required argument, and similar code works elsewhere