Add Filters To The s2 plugin form input values

// if a button is hidden, show only other
                $unsubscribe_value = apply_filters( 's2_unsubscribe_text', __('Unsubscribe', 'subscribe2') );
                $subscribe_value = apply_filters( 's2_subscribe_text', __('Subscribe', 'subscribe2') );
        if ( $hide == 'subscribe' ) {
            $this->input_form_action = "<input type=\"submit\" name=\"unsubscribe\" value=\"" . esc_attr( $unsubscribe_value ) . "\" />";
        } elseif ( $hide == 'unsubscribe' ) {
            $this->input_form_action = "<input type=\"submit\" name=\"subscribe\" value=\"" . esc_attr( $subscribe_value ) . "\" />";
        } else {
            // both form input actions
            $this->input_form_action = "<input type=\"submit\" name=\"subscribe\" value=\"" . esc_attr( $subscribe_value ) . "\" />&nbsp;<input type=\"submit\" name=\"unsubscribe\" value=\"" . esc_attr( $unsubscribe_value ) . "\" />";
        }