Just tired with seemingly infinite try ... finally or with ... as.

defers.py

# WTFPL
import functools

class Defers:
    def __init__(self):
        self._defereds = []

    def add_defer(self, defer_func):
        self._defereds.append(defer_func)

    def aswith(self, enterable, *, fallback=None):
        if fallback is None:
            f = enterable.__enter__()
        else:
            try:
                f = enterable.__enter__()
            # pylint: disable=broad-except
            except Exception:
                f = fallback()
        self.add_defer(enterable.__exit__)
        return f

    def call_all_defers(self):
        for defered in self._defereds:
            defered()

    def __enter__(self):
        return self

    def __exit__(self, type_, value, tb):
        self.call_all_defers()

    def open(self, *args, **kwargs):
        return self.aswith(open(*args, **kwargs))

    def defers(self, func):
        self.add_defer(func)
        return func

example-usage.py

with Defers() as d:
    f1 = open("file1")
    @d.defers
    def finally_block():
        f1.close()
    f2 = d.aswith(open("file2"))
    f3 = d.open("file3")