human
Solve the following python programming problem given the following code:
def get_change_form(self, is_post, fields) : 
    edit_view = self.get_model_view (ModelFormAdminView, self.model) 
    def formfield_for_dbfield(db_field, **kwargs) : 
        formfield = edit_view.formfield_for_dbfield (db_field, required = is_post, ** kwargs) 
        formfield.widget = ChangeFieldWidgetWrapper (formfield.widget) 
        return formfield 
defaults = { 
        'form' : edit_view.form, 
        'fields' : fields, 
        'formfield_callback' : <MASK>, 
} 
    return modelform_factory (self.model, ** defaults) 
    
    Given the code above, what is a proper replacement for <MASK>?
assistant
#Here is a proper replacement for <MASK>.
formfield_for_dbfield