I have such part in my script, how can I optimize such parts?  I don't want to use many local variables.size_variants = []for size in sizes_list:    size_variants.append({'size': size})Also here:variants_tmp = list()all_color_list = list(get_all_colors())[variants_tmp.extend(var) for var in all_color_list]
Optimizing and clarifying nested list appending
python;optimization
Using a list comprehension means you can eliminate all local variables:size_variants = [{'size': size} for size in sizes_list]Generally, anything of the form:<new list initialization>for <variable> in <list>:    <new list>.append(<variable>)can be written much more cleanly in list comprehension form.Edit: If you want to extend an already existing list, and you have something like a nested list, then you'll probably want to use itertools.chain:import itertoolsx = [1, 2, 3]y = [[4, 5], [6, 7, 8], [9, 10]x = x + [i for i in itertools.chain.from_iterable(y)]which will have x == [1, 2, 3, 4, 5, 6, 7, 8, 9, 10].