> There are a couple ways to do almost everything in Python; loops or map, Twisted or threads, unittest2 or nose, and so on

There are always more than 1 ways to do something, but Python tries to be directive towards the recommended way for the core.

For the given snippet, using reduce for loops is frowned upon; nothing is stopping you from doing it, but the general opinion is you shouldn't do it. I think that counts as there being an obvious way.

    def pipe(val, fns):
        return reduce(lambda val, fn: fn(val), fns, val)

    def pipe2(val, fns):
        for fn in fns:
            val = fn(val)
        return val

    fns = [lambda x: x + 1, lambda x: x * x]
    print pipe(5, fns)

    print pipe2(5, fns)

As far as maps and list comprehension go, that isn't clear-cut but people incline towards comprehensions.

<nitpick> Twisted(reactors) and threads implement two different things which serve different purposes, and unittest2 is a lib while nose is a test runner. </nitpick>

That said, there is always going to be many ways to do something, but it helps if the core tries to stick with a uniform way to do things.