foo()
foo(a)
foo(a,)
foo(a=10)
foo(a,b)
foo(a,b=10)
foo(a=10,b=10)
foo(a,b,c,*d)
foo(a,b,c,*d,e=10)
foo(a,b,c=10,*d,**kw)
foo(a,b,c=10,*d,e=10,**kw)
foo(*d,c=10,d=20,**kw)
foo(**kw)

foo(a)(b)(c,d)(a=10,**kw)
