[player] use real physics force
[player] node_physics_simulate
-- move by velocity
and clear force
for every node_model
[player] remove node_physics_fake_simulate
[player] draw_net
-- print non-wire value -- test by list-map.play.lisp
[lang] [maybe] write arity checker in inet-lisp itself!
[lang] write the arity checker like a type checker -- choose good names in the problem domain
[lang] check arity -- compute arity from exp
[lang] compute arity
from each exp -- what should be the function names?
[lang] compile_exp
-- EXP_AP
-- should not get arity
from list_length(exp->ap.arg_list)
[lang] apply_function
-- supplement wire if arity is short
improve undefined-node.error.lisp
[testing] (assert)
report position