While building dbt-core- sql-python pipe with following code in .py file , getting error as - "dbt allows exactly one model defined per python file, found 0"

[PawanKumarAgrawal]

# Import necessary libraries
import numpy as np
import pandas as pd

def my_first_python_model(dbt, session):
    # dbt configuration
    dbt.config(
                materialized='table',
                description='My_first_Python_model',
                tags=['python']
                )

    # get upstream data
    my_first_dbt_model_result = dbt.ref("my_first_dbt_model").to_pandas()

    # Additional Python-based transformations
    # Concatenate columns 'FirstName', 'MiddleName', and 'LastName' into a new column 'FullName'
    my_first_dbt_model_result['FullName'] = my_first_dbt_model_result[['FirstName', 'MiddleName', 'LastName']].apply(lambda x: ' '.join(x.dropna()), axis=1)

    # Print the transformed DataFrame
    print(my_first_dbt_model_result[['FullName']])

    # Return the DataFrame as a dbt table
    return my_first_dbt_model_result[['FullName']]

[PawanKumarAgrawal]

Please help