How to load and use a PARI/GP script in Sage notebook?

Take for example the script http://math.stanford.edu/~stange/scripts/tate_via_nets.gp What I do is copying the script to a txt file and name it tatepairing.gp. Then I go to my sage notebook and choose above the option 'gp'. In the first block I write "\r filename" where filename is the whole path of the file tatepairing.gp (so C:....\tatepairing.gp) and evaluate it. If you go to the link you see a function tate_pairing_alg with input an elliptic curve, two points on it and an integer. Therefore I define (over $\mathbb{F}_5$) e = ellinit([0,0,0,4,0]*Mod(1,5)) P1= [2,4] P2=[1,0]

Now I do tate_pairing_alg(e, P1, P2, 4), the answer is

* at top-level: tatepairing.tate_pairing_alg(e,P ^-------------------- ** not a function in function call

If you see me doing things wrongly please let me know it :-) Thanks