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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def formfield_for_dbfield(self, db_field, **kwargs):
 """ Override the default widget for Foreignkey fields if they are specified in the related_search_fields class attribute. """

        if isinstance(db_field, models.ForeignKey) and db_field.name in self.related_search_fields:
            help_text = self.get_help_text(db_field.name, db_field.remote_field.model._meta.object_name)
            if kwargs.get('help_text'):
                help_text = six.u('%s %s' % (kwargs['help_text'], help_text))
            kwargs['widget'] = ForeignKeySearchInput(db_field.remote_field, self.related_search_fields[db_field.name])
            kwargs['help_text'] = help_text
        return super(ForeignKeyAutocompleteAdminMixin, self).formfield_for_dbfield(db_field, **kwargs)