deep_add.py

from __future__ import annotations

from functools import reduce
from operator import add
from typing import Sequence, Union, Iterable, Any

NumberTypes = (int, float, complex,)
Number = Union[NumberTypes]
NestedSequences = Union[Number, Sequence['NestedSequences']]


def flatten(items, ignore_types=(str, bytes)):
    for x in items:
        if isinstance(x, Iterable) and not isinstance(x, ignore_types):
            yield from flatten(x, ignore_types)
        else:
            yield x


def deep_add(seq: NestedSequences, start: Any = 0) -> int:
    """
    >>> deep_add([1, 2, 3, 4])
    10
    >>> deep_add([[1, 2, 3], [4, 5, 6]])
    21
    >>> deep_add([[[1, 2], [3, 4]], [[5, 6], [7, 8]]])
    36

    Bonus 1:
    >>> deep_add([(1, 2), [3, {4, 5}]])
    15

    Bonus 2:
    >>> deep_add([[1, 2], [3, 4]], start=2)
    12

    Bonus 3:
    >>> from datetime import timedelta
    >>> deep_add([[timedelta(5), timedelta(10)], [timedelta(3)]], start=timedelta(0))
    18
    """
    flat = list(flatten(seq))
    typ = type(flat[0]) if len(flat) else int
    if len(flat) == 0:
        flat.append(0)
    result = reduce(add, flat)
    if typ in NumberTypes:
        return result + start
    else:
        return (result + start) / typ(1)