Try using * unpack, like below:
>>> a=set('abcde')
>>> a
{'a', 'd', 'e', 'b', 'c'}
>>> l=['f','g']
>>> l
['f', 'g']
>>> {*l, *a}
{'a', 'd', 'e', 'f', 'b', 'g', 'c'}
>>>
Non Editor version:
a=set('abcde')
l=['f', 'g']
print({*l, *a})
Output:
{'a', 'd', 'e', 'f', 'b', 'g', 'c'}