Algorithm that would take one string and one list ( of single characters ) from the user and would display the all occurrences of all the characters(given in the list) in the string.

algo.py

def get_indices(s, lst):
    indice = list()
    indices = list()
    toReturn = ''
    for char in lst:
        for i in range(len(s)):
            if s[i] == char:
                indice.append(i)
        indices.append(indice)
        indice = []
    for i in range(len(lst)):
        toReturn+=f"Appearances of '{lst[i]}': "
        for index in indices[i]:
            toReturn+=f'{index}, '
        toReturn = toReturn[:-2] + '\n'

    return toReturn[:-1]
    
# Test 
print(get_indices('lol you comedy me? you better not as i am a chad', ['o', 'e', 'a']))

# Output
# Appearances of 'o': 1, 5, 9, 20, 31
# Appearances of 'e': 11, 16, 24, 27
# Appearances of 'a': 34, 39, 42, 46