Find unique words in a sentence and mark their positions

unique_words_with_position.py

import string

sentence = input("Please enter a sentence \n")

translator = str.maketrans({key: None for key in string.punctuation})
words = sentence.translate(translator).lower().split()

def indices(source_list, item):
    return [index for index, value in enumerate(source_list) if value == item]

indexed_words = {word: indices(words, word) for word in set(words)}