Javascript-like "let" variables. From https://nvbn.github.io/2014/09/25/let-statement-in-python/

let.py

from contextlib import contextmanager
from inspect import currentframe, getouterframes

@contextmanager
def let(**bindings):
    frame = getouterframes(currentframe(), 2)[-1][0] # 2 because first frame in `contextmanager` decorator  
    locals_ = frame.f_locals
    original = {var: locals_.get(var) for var in bindings.keys()}
    locals_.update(bindings)
    yield
    locals_.update(original)