How to use the radian.settings.radian_settings.tab_size function in radian

def _(event):
        text = event.current_buffer.document.text_before_cursor
        textList = text.split("\n")
        if len(textList) >= 2:
            m = re.match(r"^\s*$", textList[-1])
            if m:
                current_indentation = m.group(0)
                previous_indentation = re.match(r"^\s*", textList[-2]).group(0)
                tab_size = settings.tab_size
                if len(current_indentation) >= settings.tab_size and \
                        current_indentation == previous_indentation:
                    event.current_buffer.delete_before_cursor(tab_size)

        event.current_buffer.insert_text(event.data)

def _(event):
        text = event.current_buffer.document.text_before_cursor
        textList = text.split("\n")
        if len(textList) >= 2:
            m = re.match(r"^\s*$", textList[-1])
            if m:
                current_indentation = m.group(0)
                previous_indentation = re.match(r"^\s*", textList[-2]).group(0)
                tab_size = settings.tab_size
                if len(current_indentation) >= settings.tab_size and \
                        current_indentation == previous_indentation:
                    event.current_buffer.delete_before_cursor(tab_size)

        event.current_buffer.insert_text(event.data)

def _(event):
        tab_size = settings.tab_size
        buf = event.current_buffer
        leading_spaces = len(buf.document.text_before_cursor)
        buf.delete_before_cursor(min(tab_size, leading_spaces))

def _(event):
        copy_margin = not in_paste_mode() and settings.auto_indentation
        event.current_buffer.newline(copy_margin=copy_margin)
        if settings.auto_indentation:
            tab_size = settings.tab_size
            event.current_buffer.insert_text(" " * tab_size)
        event.current_buffer.insert_text("\n")
        event.current_buffer.cursor_position -= 1