sum_of_elements  = sum()
elementwise_sum  = [sum(pair) for pair in zip(list_a, list_b)]
sorted_by_second = sorted(, key=lambda el: el[1])
sorted_by_both   = sorted(, key=lambda el: (el[1], el[0]))
flatter_list     = list(itertools.chain.from_iterable())
product_of_elems = functools.reduce(lambda out, el: out * el, )
list_of_chars    = list()