Flattens nested lists/tuples into a single flat list.

flatten.py

# Flattens nested lists/tuples into a single flat list. Other typles are
# returned as-is.
#
#
# Sample usage:
#
#   >>> flatten([1, 2, 3, 4])
#   [1, 2, 3, 4]
#
#   >>> flatten([1, [2, 3], 4])
#   [1, 2, 3, 4]
#
#   >>> flatten([1, [2, [3]], 4])
#   [1, 2, 3, 4]
#
#   >>> flatten((1, (2, [3]), 4))
#   [1, 2, 3, 4]
#
#   >>> flatten((1, (2, (3)), 4))
#   [1, 2, 3, 4]
#
#   >>> flatten((1, (2, (3)), {'a': 1}, 4))
#   [1, 2, 3, {'a': 1}, 4]
#
def flatten(l):
    if not isinstance(l, list) and not isinstance(l, tuple) :
        return [l]

    resulting_list = []

    for item in l:
        resulting_list.extend(flatten(item))

    return resulting_list