def _(event: E) -> None:
        """
        Space: remove line from default pane.
        """
        b = event.current_buffer
        line_no = b.document.cursor_position_row - history_mapping.result_line_offset

        if line_no >= 0:
            try:
                history_lineno = sorted(history_mapping.selected_lines)[line_no]
            except IndexError:
                pass  # When `selected_lines` is an empty set.
            else:
                history_mapping.selected_lines.remove(history_lineno)

            history_mapping.update_default_buffer()

        Space: remove line from default pane.
        
src/ptpython/history_browser.py