def _merge_styles(self,

                      new_style: odf.style.Style,

                      sources: Iterable[odf.style.Style],

    ) -> None:

        for elem in sources:

            for key, new_value in self.iter_attributes(elem):

                old_value = new_style.getAttribute(key)

                if (key == 'name'

                    or key == 'displayname'

                    or old_value == new_value):

                    pass

                elif old_value is None:

                    new_style.setAttribute(key, new_value)

                else:

                    raise ValueError(f"cannot merge styles with conflicting {key}")

            for child in elem.childNodes:

                new_style.addElement(self.copy_element(child))

    def merge_styles(self,

                     *styles: Union[str, odf.style.Style, None],

    ) -> Optional[odf.style.Style]:

        """Create a new style from multiple existing styles

        Given any number of existing styles, create a new style that combines

        all of those styles' attributes and properties, add it to the document

        styles, and return it.

        Styles can be specified by name, or by passing in their Style element.

        For convenience, you can also pass in None as an argument; None will

        simply be skipped.

        Results are cached. If you repeatedly call this method with the same

        arguments, you'll keep getting the same style returned, which will

        only be added to the document once.

        If you pass in zero real style arguments, returns None.

        If you pass in one style argument, returns that style unchanged.

        If you pass in a style that doesn't already exist in the document,

        or if you pass in styles that can't be merged (because they have

        conflicting attributes), raises ValueError.

        """

        name_map: Dict[str, odf.style.Style] = {}

        for name in self._merge_style_iter_names(styles):

            source = odf.style.Style(name=name)

            found = self.find_child(self.document.styles, source)

            if found is None:

                raise ValueError(f"no style named {name!r}")

            name_map[name] = found

        if not name_map:

            retval = None

        elif len(name_map) == 1:

            _, retval = name_map.popitem()

        else:

            new_name = f'Merge_{"_".join(sorted(name_map))}'

            retval = self.ensure_child(

                self.document.styles, odf.style.Style, name=new_name,

            )

            if retval.firstChild is None:

                self._merge_styles(retval, name_map.values())

        return retval

    ### Sheets

    def lock_first_column(self, sheet: Optional[odf.table.Table]=None) -> None:

        """Lock the first column of cells under the given sheet

        This method sets all the appropriate settings to "lock" the first column

        of cells in a sheet, so it stays in view even as the viewer scrolls

        across the sheet. If a sheet is not given, works on ``self.sheet``.

        """

        if sheet is None:

            sheet = self.sheet

        config_map = self.ensure_config_map_entry(

            self.view, 'Tables', sheet.getAttribute('name'),

        )

        self.set_config(config_map, 'PositionRight', 1, 'int')

        self.set_config(config_map, 'HorizontalSplitMode', 2, 'short')

        self.set_config(config_map, 'HorizontalSplitPosition', 1, 'short')

    def lock_first_row(self, sheet: Optional[odf.table.Table]=None) -> None:

        """Lock the first row of cells under the given sheet

        This method sets all the appropriate settings to "lock" the first row

        of cells in a sheet, so it stays in view even as the viewer scrolls

        through rows. If a sheet is not given, works on ``self.sheet``.

        """

        if sheet is None:

            sheet = self.sheet

        config_map = self.ensure_config_map_entry(

            self.view, 'Tables', sheet.getAttribute('name'),

        )

        self.set_config(config_map, 'PositionBottom', 1, 'int')

        self.set_config(config_map, 'VerticalSplitMode', 2, 'short')

        self.set_config(config_map, 'VerticalSplitPosition', 1, 'short')

    def set_open_sheet(self, sheet: Union[str, odf.table.Table, None]=None) -> None:

        """Set which sheet is open in the document

        When the user first opens the spreadsheet, their view will be on this

        sheet. You can provide a sheet name string or sheet object. With no

        argument, defaults to ``self.sheet``.

        """

        if sheet is None:

            sheet = self.sheet

        if not isinstance(sheet, str):

            sheet = sheet.getAttribute('name')

            if not isinstance(sheet, str):

                raise ValueError("sheet argument has no name for setting")

        self.set_config(self.view, 'ActiveTable', sheet, 'string')

    def use_sheet(self, name: str) -> odf.table.Table:

        """Switch the active sheet ``self.sheet`` to the one with the given name

        If there is no sheet with the given name, create it and append it to

        the spreadsheet first.

        If the current active sheet is empty when this method is called, it

        will be removed from the spreadsheet.

        """

        try:

            empty_sheet = not self.sheet.hasChildNodes()

        except AttributeError:

            empty_sheet = False

        if empty_sheet:

            self.document.spreadsheet.removeChild(self.sheet)

        self.sheet = self.ensure_child(

            self.document.spreadsheet, odf.table.Table, name=name,

        )

        return self.sheet

    ### Initialization hooks

    def init_settings(self) -> None:

        """Hook called to initialize settings

        This method is called by __init__ to populate

        ``self.document.settings``. This implementation creates the barest

        skeleton structure necessary to support other methods, in particular

        ``lock_first_row``.

        """

        view_settings = self.ensure_child(

            self.document.settings, odf.config.ConfigItemSet, name='ooo:view-settings',

        )

        views = self.ensure_child(

            view_settings, odf.config.ConfigItemMapIndexed, name='Views',

        )

        self.view = self.ensure_child(views, odf.config.ConfigItemMapEntry)

        self.set_config(self.view, 'ViewId', 'view1')

    def init_styles(self) -> None:

        """Hook called to initialize settings

        This method is called by __init__ to populate

        ``self.document.styles``. This implementation creates basic building

        block cell styles often used in financial reports.

        """

        styles = self.document.styles

        self.style_bold = self.ensure_child(

            styles, odf.style.Style, name='Bold', family='table-cell',

        )

        self.ensure_child(

            self.style_bold, odf.style.TextProperties, fontweight='bold',

        )

        date_style = self.replace_child(styles, odf.number.DateStyle, name='ISODate')

        date_style.addElement(odf.number.Year(style='long'))

        date_style.addElement(odf.number.Text(text='-'))

        date_style.addElement(odf.number.Month(style='long'))

        date_style.addElement(odf.number.Text(text='-'))

        date_style.addElement(odf.number.Day(style='long'))

        self.style_date = self.ensure_child(

            styles,

            odf.style.Style,

            name=f'{date_style.getAttribute("name")}Cell',

            family='table-cell',

            datastylename=date_style,

        )

        self.style_starttext: odf.style.Style

        self.style_centertext: odf.style.Style

        self.style_endtext: odf.style.Style

        for textalign in ['start', 'center', 'end']:

            aligned_style = self.replace_child(

                styles, odf.style.Style, name=f'{textalign.title()}Text',

            )

            aligned_style.setAttribute('family', 'table-cell')

            aligned_style.addElement(odf.style.ParagraphProperties(textalign=textalign))

            setattr(self, f'style_{textalign}text', aligned_style)

    ### Properties

    def set_properties(self, *,

                       created: Optional[datetime.datetime]=None,

                       generator: str='conservancy_beancount',

    ) -> None:

        if created is None:

            created = datetime.datetime.now()

        created_elem = self.ensure_child(self.document.meta, odf.meta.CreationDate)

        created_elem.childNodes.clear()

        created_elem.addText(created.isoformat())

        generator_elem = self.ensure_child(self.document.meta, odf.meta.Generator)

        generator_elem.childNodes.clear()

        generator_elem.addText(f'{generator}/{VERSION} {TOOLSVERSION}')

    ### Rows and cells

    def add_row(self, *cells: odf.table.TableCell, **attrs: Any) -> odf.table.TableRow:

        row = odf.table.TableRow(**attrs)

        for cell in cells:

            row.addElement(cell)

        self.sheet.addElement(row)

        return row

    def balance_cell(self, balance: Balance, **attrs: Any) -> odf.table.TableCell:

        balance = balance.clean_copy() or balance

        balance_currency_count = len(balance)

        if balance_currency_count == 0:

            return self.float_cell(0, **attrs)

        elif balance_currency_count == 1:

            amount = next(iter(balance.values()))

            attrs['stylename'] = self.merge_styles(

                attrs.get('stylename'), self.currency_style(amount.currency),

            )

            return self.currency_cell(amount, **attrs)

        else:

            lines = [babel.numbers.format_currency(

                number, currency, locale=self.locale, format_type=self.currency_fmt_key,

            ) for number, currency in balance.values()]

            attrs['stylename'] = self.merge_styles(

                attrs.get('stylename'), self.style_endtext,

            )

            return self.multiline_cell(lines, **attrs)

    def currency_cell(self, amount: data.Amount, **attrs: Any) -> odf.table.TableCell:

        if 'stylename' not in attrs:

            attrs['stylename'] = self.currency_style(amount.currency)

        number, currency = amount

        cell = odf.table.TableCell(valuetype='currency', value=number, **attrs)

        cell.addElement(odf.text.P(text=babel.numbers.format_currency(

            number, currency, locale=self.locale, format_type=self.currency_fmt_key,

        )))

        return cell

    def date_cell(self, date: datetime.date, **attrs: Any) -> odf.table.TableCell:

        attrs.setdefault('stylename', self.style_date)

        cell = odf.table.TableCell(valuetype='date', datevalue=date, **attrs)

        cell.addElement(odf.text.P(text=date.isoformat()))

        return cell

    def float_cell(self, value: Union[int, float, Decimal], **attrs: Any) -> odf.table.TableCell:

        cell = odf.table.TableCell(valuetype='float', value=value, **attrs)

        cell.addElement(odf.text.P(text=str(value)))

        return cell

    def _meta_link_pairs(self, links: Iterable[Optional[str]]) -> Iterator[Tuple[str, str]]:

        for href in links:

            if href is None:

                continue

            elif self.rt_wrapper is not None:

                rt_ids = self.rt_wrapper.parse(href)

                rt_href = rt_ids and self.rt_wrapper.url(*rt_ids)

            else:

                rt_ids = None

                rt_href = None

            if rt_ids is None or rt_href is None:

                # '..' pops the ODS filename off the link path. In other words,

                # make the link relative to the directory the ODS is in.

                href_path = Path('..', href)

                href = str(href_path)

                text = href_path.name

            else:

                rt_path = urlparse.urlparse(rt_href).path

                if rt_path.endswith('/Ticket/Display.html'):

                    text = rtutil.RT.unparse(*rt_ids)

                else:

                    text = urlparse.unquote(Path(rt_path).name)

                href = rt_href

            yield (href, text)

    def meta_links_cell(self, links: Iterable[Optional[str]], **attrs: Any) -> odf.table.TableCell:

        return self.multilink_cell(self._meta_link_pairs(links), **attrs)

    def multiline_cell(self, lines: Iterable[Any], **attrs: Any) -> odf.table.TableCell:

        cell = odf.table.TableCell(valuetype='string', **attrs)

        for line in lines:

            cell.addElement(odf.text.P(text=str(line)))

        return cell

    def multilink_cell(self, links: Iterable[LinkType], **attrs: Any) -> odf.table.TableCell:

        cell = odf.table.TableCell(valuetype='string', **attrs)

        for link in links:

            if isinstance(link, tuple):

                href, text = link

            else:

                href = link

                text = None

            cell.addElement(odf.text.P())

            cell.lastChild.addElement(odf.text.A(

                type='simple', href=href, text=text or href,

            ))

        return cell

    def string_cell(self, text: str, **attrs: Any) -> odf.table.TableCell:

        cell = odf.table.TableCell(valuetype='string', **attrs)

        cell.addElement(odf.text.P(text=text))

        return cell

    def write_row(self, row: RT) -> None:

        """Write a single row of input data to the spreadsheet

        This default implementation adds a single row to the spreadsheet,

        with one cell per element of the row. The type of each element

        determines what kind of cell is created.

        This implementation will help get you started, but you'll probably

        want to override it to specify styles.

        """

        out_row = odf.table.TableRow()

        for cell_source in row:

            if isinstance(cell_source, (int, float, Decimal)):

                cell = self.float_cell(cell_source)

            else:

                cell = self.string_cell(cell_source)

            out_row.addElement(cell)

        self.sheet.addElement(out_row)

    def save_file(self, out_file: BinaryIO) -> None:

        self.document.write(out_file)

    def save_path(self, path: Path, mode: str='w') -> None:

        with path.open(f'{mode}b') as out_file:

            out_file = cast(BinaryIO, out_file)

            self.save_file(out_file)

def account_balances(

        groups: Mapping[data.Account, PeriodPostings],

        order: Optional[Sequence[str]]=None,

) -> Iterator[Tuple[str, Balance]]:

    """Iterate account balances over a date range

    1. ``subclass = PeriodPostings.with_start_date(start_date)``

    2. ``groups = dict(subclass.group_by_account(postings))``

    3. ``for acct, bal in account_balances(groups, [optional ordering]): ...``

    This function returns an iterator of 2-tuples ``(account, balance)``

    that you can use to generate a report in the style of ``ledger balance``.

    The accounts are accounts in ``groups`` that appeared under one of the

    account name strings in ``order``. ``balance`` is the corresponding

    balance over the time period (``groups[key].period_bal``). Accounts are

    iterated in the order provided by ``sort_and_filter_accounts()``.

    The first 2-tuple is ``(OPENING_BALANCE_NAME, balance)`` with the balance of

    all these accounts as of ``start_date``.

    The final 2-tuple is ``(ENDING_BALANCE_NAME, balance)`` with the final

    balance of all these accounts as of ``start_date``.

    The iterator will always yield these special 2-tuples, even when there are

    no accounts in the input or to report.

    """

    if order is None:

        order = ['Equity', 'Income', 'Expenses']

    acct_seq = [account for _, account in sort_and_filter_accounts(groups, order)]

    yield (OPENING_BALANCE_NAME, sum(

        (groups[key].start_bal for key in acct_seq),

        MutableBalance(),

    ))

    for key in acct_seq:

        postings = groups[key]

        try:

            in_date_range = postings[-1].meta.date >= postings.START_DATE

        except IndexError:

            in_date_range = False

        if in_date_range:

            yield (key, groups[key].period_bal)

    yield (ENDING_BALANCE_NAME, sum(

        (groups[key].stop_bal for key in acct_seq),

        MutableBalance(),

    ))

def normalize_amount_func(account_name: str) -> Callable[[T], T]:

    """Get a function to normalize amounts for reporting

    Given an account name, return a function that can be used on "amounts"