# TLDR; Extend is faster than a an append loop
def append(alist, iterable):
    for item in iterable:
        alist.append(item)
        
def extend(alist, iterable):
    alist.extend(iterable)

import timeit

>>> min(timeit.repeat(lambda: append([], "abcdefghijklmnopqrstuvwxyz")))
2.867846965789795
>>> min(timeit.repeat(lambda: extend([], "abcdefghijklmnopqrstuvwxyz")))
0.8060121536254883