`
>>> def foo(num=1):
...     return num
...
>>> foo(*(bool,) is bool else *())
  File "<stdin>", line 1
    foo(*(bool,) is bool else *())
                         ^
SyntaxError: invalid syntax
>>> foo(*(bool,) if bool else *())
  File "<stdin>", line 1
    foo(*(bool,) if bool else *())
                              ^
SyntaxError: invalid syntax
>>> def foo(num=1):
...     return num
...
>>> stri = ''
>>> foo(*(stri,) if stri else *())
  File "<stdin>", line 1
    foo(*(stri,) if stri else *())
                              ^
SyntaxError: invalid syntax
>>> foo(*((stri,) if stri else ()))
1
>>>
`

Iterable unpacking of empty tuple seems to not work in one example but does in another.