flatten a list of lists in python

list_flatten.py

# Original discussion
# https://stackoverflow.com/questions/952914/making-a-flat-list-out-of-list-of-lists-in-python

# vanilla python list comprehension
flatten = lambda lst: [item for sublist in lst for item in sublist]

# with itertools
flatten_chain = lambda lst: list(itertools.chain(*lst))

# with itertools >= 2.6
flatten_chain2 = lambda lst: list(itertools.chain.from_iterable(lst))