Python response to https://extras.waynewbishop.com/challenge/reverse-vowels

reverse_only_vowels.py

string = input("Which string you want to vowel-reverse?\n> ")
listed_string = list(string)

# Helper function to find whether a character is a vowel
def is_vowel(c):
    """Determines is c is a vowel; returns False if it is not, True if it is."""
    result = False
    vowel_list = list("aeiou")
    try:
        position = vowel_list.index(c)
        result = True
    except ValueError as e:
        pass # nothing to do if it is not in there
    return result

def index_of_true(a_list, a_true_function):
    return [idx for idx, x in enumerate(a_list) if a_true_function(x)]

def reverse_list(a_list):
    return [a_list[len(a_list)-i-1] for i in range(0,len(a_list))]

vowels_indexes = index_of_true(listed_string, is_vowel)

def swap_items_from_pairs(a_list, list_of_pairs):
    result_list = a_list.copy()
    for v_idx1, v_idx2 in list_of_pairs:
        c1 = result_list[v_idx1]
        c2 = result_list[v_idx2]
        result_list[v_idx2] = c1
        result_list[v_idx1] = c2
    return result_list

# Reversing indexes without reverse function
reversed_indexes = reverse_list(vowels_indexes)
list_of_swaps = [(x,y) for x,y in zip(reversed_indexes, vowels_indexes)]
list_of_swaps = list_of_swaps[:(len(list_of_swaps)//2)] # truncate to integer half: i.e. 3//2 --> 1

print("".join(swap_items_from_pairs(listed_string, list_of_swaps)))