How to flatten a python nested list(tuple)

flatten.py

flatten = lambda lst: reduce(lambda l, i: l + flatten(i) if isinstance(i, (list, tuple)) else l + [i], lst, [])  

print flatten([2, [2, [4, 5, [7], [2, [6, 2, 6, [6], 4]], 6]]])
# -> [2, 2, 4, 5, 7, 2, 6, 2, 6, 6, 4, 6]

I've stumbled upon this gist in google search results :-)

I've made tail-recursive python 3 version available here: https://gist.github.com/shaxbee/0ada767debf9eefbdb6e

enhanced version of shaxbee's solution, https://gist.github.com/ma-ric/451ce328c4c84d18c8af