itertools.chain.from_iterable.md

In [1]: from itertools import chain

In [2]: x = [{1: 2}, {3: 4}, None]

In [3]: {k: v for k, v in chain.from_iterable(d.iteritems() for d in x if d is not None)}
Out[3]: {1: 2, 3: 4}

See: http://docs.python.org/2/library/itertools.html#itertools.chain.from_iterable