"Should Be in the STDlib" - aka. my helper library, which has outgrown it's original name

sbstd.py

# Really useful in some situations, but you can see how often it's actually been used, since cmp() doesn't even exist anymore...
sign = lambda v: cmp(v, 0)

clamp = lambda v, minv, maxv: min(max(v, minv), maxv)
# These are a bit of a misnomers, since below/above suggests lt/gt, while these are le/ge
clamp_below = lambda v, maxv: min(v, maxv)
clamp_above = lambda v, minv: max(v, minv)

div_ceil = lambda dividend, divisor: (dividend - 1) // divisor + 1
# Just for symmetry
div_floor = lambda dividend, divisor: dividend // divisor
align_up = lambda dividend, divisor: div_ceil(dividend, divisor) * divisor
align_down = lambda dividend, divisor: div_floor(dividend, divisor) * divisor

def chunk(data, chunksize):
        islice = itertools.islice
        it = iter(data)
        return iter(lambda: tuple(islice(it, chunksize)), ())

def collapse(*args):
        if len(args) == 1:
                args = args[0]
        items = iter(args)
        value = next(items)
        for item in items:
                assert item == value, 'Expected all values to be identical; %r != %r' % (item, value)
        return value


# These were borrowed, since I saw their usefullness, but I haven't really ended up using them at all
# from pyrtsa @ #python.fi @ ircnet, https://gist.github.com/1310524
take = lambda l, n: l[slice(n, None) if n < 0 else slice(n)]
drop = lambda l, n: l[slice(n) if n < 0 else slice(n, None)]

# do not take/drop if n is negative
take_head = lambda l, n: take(l, max(n, 0))
take_tail = lambda l, n: take(l, -max(n, 0))
drop_head = lambda l, n: drop(l, max(n, 0))
drop_tail = lambda l, n: drop(l, -max(n, 0))