from itertools import product
list(map(''.join, product('abc', 'def','hg')))

from itertools import product
import re

def string_combos(s):
    # get all expressions inside brackets into a list
    brackets = re.findall(r'{(.+?)}', s)

    # remove comas 
    joined_chars_list = [''.join(b.split(',')) for b in brackets]

    # In the above line the b.split(',') could be turned into another
    # list comprehension to remove whitespace if it is acceptable as
    # a part of input string

    # E.g. if this is acceptable:
    # string_combos('{a, b}{ c , d}{ e,   f}')

    # Then use something like:
    # [char_part.strip() for char_part in b.split(',')]
    
    return [''.join(p) for p in product(*joined_chars_list)] # copy of what scidam posted but I find this way easier to read than "list(map(" way
    
result = string_combos('{a,b}{c,d}{e,f}')
print(result)

Output:
['ace', 'acf', 'ade', 'adf', 'bce', 'bcf', 'bde', 'bdf']