def get_form_kwargs(self):
        """
        Check for and add "child" and "timer" from request query parameters.
          - "child" may provide a slug for a Child instance.
          - "timer" may provided an ID for a Timer instance.

        These arguments are used in some add views to pre-fill initial data in
        the form fields.

        :return: Updated keyword arguments.
        """
        kwargs = super(CoreAddView, self).get_form_kwargs()
        for parameter in ["child", "timer"]:
            value = self.request.GET.get(parameter, None)
            if value:
                kwargs.update({parameter: value})
        return kwargs

        Check for and add "child" and "timer" from request query parameters.
          - "child" may provide a slug for a Child instance.
          - "timer" may provided an ID for a Timer instance.

        These arguments are used in some add views to pre-fill initial data in
        the form fields.

        :return: Updated keyword arguments.
        
core/views.py