Theme_My_Login_Form::get_action()

public function get_action() {
    /**
     * Filters the form action.
     *
     * @since 7.0
     *
     * @param string              $action The form action.
     * @param Theme_My_Login_Form $this   The form object.
     */
    return apply_filters( 'tml_get_form_action', $this->action, $this );
}

View src/includes/class-theme-my-login-form.php, line 158 on GitHub