not not for bool conversions

Using two not operators instead of the built-in bool function is usually faster when wanting to convert some value to a boolean value:

>>> for t in ('bool(foo)', 'not not foo'):
        timeit(t, setup='foo = 5')


Dynamic tree

A dynamic tree can be created by using a recursive defaultdict:

from collections import defaultdict
tree = lambda: defaultdict(tree)

t = tree()
t['dynamic']['path']['to']['something'] = 'foo'
print(t['dynamic']['path']['to']['something']) # foo