Sum or concatenate

#! /usr/bin/env python3

from random import randint as rnd

# Task: make a function that takes zero to three arguments. Each
# argument may be either an integer or a string. The function must
# either sum or concatenate its arguments.

def aoc(*args):
    # a list for results
    res = []
    # check if any of the arguments are strings
    string_flag = any(map((lambda x: type(x) == str), args))
    # if some arguments are strings
    if string_flag:
        # iterate through the arguments
        for arg in args:
            # check if the argument is an integer, which in this case
            # it shouldn't be
            if type(arg) == int:
                # convert to a string and append to the list of results
                res.append(str(arg))
            else:
                # or just append to the list of results
                res.append(arg)
        # turn the result list into a string by interspersing its
        # items with an empty string and concatenating the sequence
        return "".join(res)
    # if all arguments are integers, just sum them
    else:
        return sum(args)

####### Testing #######

# Patterns for combining integers and strings are binary
# representations of numbers 2 to 16 with the first digit
# removed: '0', '1', '00', '01', '10', '11', '000', '001', '010',
# '011', '100', '101', '110', '111'
cp = [bin(i)[3:] for i in range(2, 16)]

for combination in cp:
    # Depending on the combination every item is either a random
    # number 0 to 9 or a random ASCII character with a decimal code 97
    # to 122, i.e. any character within the range 'a' to 'z'
    args = [rnd(0, 9) if i == '0' else chr(rnd(97, 122)) for i in combination]

    # a list with an asterisk as an argument gets split into separate
    # items which are viewed by a function as separate arguments
    print(args, "-->", aoc(*args))

# [5] --> 5
# ['x'] --> x
# [8, 2] --> 10
# [3, 'd'] --> 3d
# ['z', 8] --> z8
# ['w', 'i'] --> wi
# [2, 5, 2] --> 9
# [5, 3, 'f'] --> 53f
# [5, 'h', 7] --> 5h7
# [7, 'g', 'n'] --> 7gn
# ['t', 8, 8] --> t88
# ['b', 5, 'r'] --> b5r
# ['b', 'd', 8] --> bd8
# ['h', 'p', 'w'] --> hpw