How do I map key combinations (pressing buttons simultaneously, not sequentially) in vim?

Question

How do I map key combinations(pressing buttons simultaneously, not sequentially) in vim? suppose I wanted to map the command :!python % <ENTER> to pressing the keys j and k together?

I tried :map j+k :!python % <ENTER>, :map j-k :!python % <ENTER> and :map <j-k> :!python % <ENTER> but this doesn't work.

Also, which button combinations would you recommend mapping? (please not F1, F2, ... no combination with ctrl or shift.)

Answer 1

If using scripts is acceptable for you, then there is arpeggio script which should suit your needs.