if self.startswith(prefix) and (

                prefix.endswith(self.SEP)

                or self == prefix

                or self[len(prefix)] == self.SEP

            ):

                return prefix

        return None

class Amount(bc_amount.Amount):

    """Beancount amount after processing

    Beancount's native Amount class declares number to be Optional[Decimal],

    because the number is None when Beancount first parses a posting that does

    not have an amount, because the user wants it to be automatically balanced.

    As part of the loading process, Beancount replaces those None numbers

    with the calculated amount, so it will always be a Decimal. This class

    overrides the type declaration accordingly, so the type checker knows

    that our code doesn't have to consider the possibility that number is

    None.

    """

    number: decimal.Decimal

class Metadata(MutableMapping[MetaKey, MetaValue]):

    """Transaction or posting metadata

    This class wraps a Beancount metadata dictionary with additional methods

    for common parsing and query tasks.

    """

    __slots__ = ('meta',)

    def __init__(self, source: MutableMapping[MetaKey, MetaValue]) -> None:

        self.meta = source

    def __iter__(self) -> Iterator[MetaKey]:

        return iter(self.meta)

    def __len__(self) -> int:

        return len(self.meta)

    def __getitem__(self, key: MetaKey) -> MetaValue:

        return self.meta[key]

    def __setitem__(self, key: MetaKey, value: MetaValue) -> None:

        self.meta[key] = value

def balance_of(txn: Transaction,

               *preds: Callable[[Account], Optional[bool]],

) -> Amount:

    """Return the balance of specified postings in a transaction.

    Given a transaction and a series of account predicates, balance_of

    returns the balance of the amounts of all postings with accounts that

    match any of the predicates.

    balance_of uses the "weight" of each posting, so the return value will

    use the currency of the postings' cost when available.

    """

    match_posts = [post for post in Posting.from_txn(txn)

                   if any(pred(post.account) for pred in preds)]

    number = decimal.Decimal(0)

    if not match_posts:

        currency = ''

    else:

        weights: Sequence[Amount] = [

            bc_convert.get_weight(post) for post in match_posts  # type:ignore[no-untyped-call]

        ]

        number = sum((wt.number for wt in weights), number)

        currency = weights[0].currency

@functools.lru_cache()

def is_opening_balance_txn(txn: Transaction) -> bool:

    opening_equity = balance_of(txn, Account.is_opening_equity)

    if not opening_equity.currency:

        return False

    rest = balance_of(txn, lambda acct: not acct.is_opening_equity())

    if not rest.currency:

        return False

    return abs(opening_equity.number + rest.number) < decimal.Decimal('.01')

    return itertools.islice(

        zip(*(itertools.cycle(seq) for seq in value_seqs)),

        stop,

    )

def parse_date(s, fmt='%Y-%m-%d'):

    return datetime.datetime.strptime(s, fmt).date()

def test_path(s):

    if s is None:

        return s

    s = Path(s)

    if not s.is_absolute():

        s = TESTS_DIR / s

    return s

def Amount(number, currency='USD'):

    return bc_amount.Amount(Decimal(number), currency)

def Cost(number, currency='USD', date=FY_MID_DATE, label=None):

    return bc_data.Cost(Decimal(number), currency, date, label)

def Posting(account, number,

            currency='USD', cost=None, price=None, flag=None,

    if cost is not None:

        cost = Cost(*cost)

        meta = None

        account,

        Amount(number, currency),

        cost,

        price,

        flag,

        meta,

    )

LINK_METADATA_STRINGS = {

    'Invoices/304321.pdf',

    'rt:123/456',

    'rt://ticket/234',

}

NON_LINK_METADATA_STRINGS = {

    '',

    ' ',

    '     ',

}

NON_STRING_METADATA_VALUES = [

    Decimal(5),

    FY_MID_DATE,

    Amount(50),

    'Equity:Funds:Unrestricted',

    'Equity:Funds:Restricted',

    'Equity:OpeningBalance',

])

class Transaction:

    def __init__(self,

                 date=FY_MID_DATE, flag='*', payee=None,

                 narration='', tags=None, links=None, postings=None,

                 **meta):

        if isinstance(date, str):

            date = parse_date(date)

        self.date = date

        self.flag = flag

        self.payee = payee

        self.narration = narration

        self.tags = set(tags or '')

        self.links = set(links or '')

        self.postings = []

        self.meta = {

            'filename': '<test>',

            'lineno': 0,

        }

        self.meta.update(meta)

            for posting in postings:

                self.add_posting(*posting)

    def add_posting(self, arg, *args, **kwargs):

        """Add a posting to this transaction. Use any of these forms:

           txn.add_posting(account, number, …, kwarg=value, …)

           txn.add_posting(account, number, …, posting_kwargs_dict)

           txn.add_posting(posting_object)

        """

        if kwargs:

            posting = Posting(arg, *args, **kwargs)

        elif args:

            if isinstance(args[-1], dict):

                kwargs = args[-1]

                args = args[:-1]

            posting = Posting(arg, *args, **kwargs)

        else:

            posting = arg

        self.postings.append(posting)

    @classmethod

    def opening_balance(cls, acct=None, **txn_meta):

        if acct is None: