in order to extend the accountReportsWidget class and add a new function, you will need to create a new module and include the following steps:

1. Create a new folder in your Odoo addons directory, and name it according to your module.

2. Create a new file called __init__.py in your module's folder.

3. Create another file called models.py in your module's folder.

4. In the models.py file, you will need to import the accountReportsWidget class and create a new class that inherits from it. Here's an example:

from odoo import api, fields, models

class ExtendedAccountReportsWidget(models.AbstractModel):
    _inherit = 'account.reports.widget'

    # Your new function here
    def your_new_function(self):
        # Your code here

1. Add your new class to the __init__.py file so it can be used by Odoo:

from . import models

1. Update the __manifest__.py file to include the new class in the models key:

'models': ['extended_account_reports_widget'],

1. Add the dependency of the account_reports_widget on your module in the manifest.py file

'depends': ['account_reports_widget'],

1. After that, you should install the module and check if it's working properly.

It's worth noting that you should test your customizations in a test environment before applying it to a production environment. Also, make sure that the class you are trying to extend is properly defined and that it's compatible with your version of Odoo.