使用functools.singledispatch装饰器简化复杂的类型判断

from collections.abc import Iterable
def flatten(source):
    if isinstance(source, Iterable) and not isinstance(source, str):
        for element in source:
            yield from flatten(element)
    else:
        yield source

from functools import singledispatch
from collections.abc import Iterable

@singledispatch
def flatten_generic(source):
    pass

@flatten_generic.register
def _(source: object):
    yield source

@flatten_generic.register
def _(source: str):
    yield source

@flatten_generic.register
def _(source: Iterable):
    for x in source:
        yield from flatten_generic(x)

@flatten_generic.register(str)
def _(source):
    yield source