Python combinations() in GP?

[hermann@stamm-wilbrandt.de]

I am porting Python code to GP.

I need Python combinations from itertools:

> > > from itertools import combinations
> > > for i in combinations(range(5),3):
...     print(i)
...
(0, 1, 2)
(0, 1, 3)
(0, 1, 4)
(0, 2, 3)
(0, 2, 4)
(0, 3, 4)
(1, 2, 3)
(1, 2, 4)
(1, 3, 4)
(2, 3, 4)
> > >

Since GP is 1-based and not 0-based at Python, I came up with this:

$ cat part.gp
sorted(v)=
{
  if(#v<2,return(1));
  if(v[1]>=v[2],return(0));
  sorted(v[2..#v]);
}

{
  forvec(v=vector(3,i,[1,5]),
    if(sorted(v),
      print(v)));
}
$

Which does the right output, but has to skip many not sorted 
combinations.
Is there a more efficient GP code for Python combinations?

$ gp -q < part.gp
[1, 2, 3]
[1, 2, 4]
[1, 2, 5]
[1, 3, 4]
[1, 3, 5]
[1, 4, 5]
[2, 3, 4]
[2, 3, 5]
[2, 4, 5]
[3, 4, 5]
$


Regards,

Hermann.