import asyncio


def showcase(a, b, /, c, d, *, e, f):
    """Some code to showcase the syntax.

    Docstrings are recognized and have an additional scope.
    Color schemas can render them differently from other strings.

    HACK doctests are highlighted too.

        >>> print('''hello
        ... world''')
    """

    @decorator(param='spam')
    async def coroutine(db:aio_db.DatabaseConnection) -> List[str]:
        r"""A coroutine."""

        await logger.log('working\x12with %r', aio_db)

        async with db.transaction():
            result = await db.query(...)
            print(f'Result: {result!r} {a=} {b=!r}')
            print(Rf'data: {c=}')
            print(rf'data: {c=}')

    mapping = None     # type: Dict[int, Any] # PEP 484

    # a regular expression
    get_regex = lambda: re.compile(     # type: ignore
        r"""\A
            word
            (?:                         # a comment
               (?P.)?
               (?P[=^])        (?# another comment)
            )?
            another word\.\.\.
            (?:\.(?P0|(?!0)\d+))?
        \Z""",
        re.VERBOSE | re.DOTALL)

    # NOTE Numbers with leading zeros are invalid in Python 3,
    # use 0o...
    answer = func(0xdeadbeef + 0b00100001 + 0123 + 0o123 +
                  1_005_123 +  # PEP 515
                  # complex numbers
                  .10e12 + 2j) @ mat

    # walrus operator
    filtered_data = [y for x in data if (y := f(x)) is not None]

    # position-only params
    bar = lambda q, w, /, e, r: (q + w + e + r)

    return R'''No escapes '\' in this \one'''