let init_cfg kf =
let env = new_cfg_env kf in
let start = add_node env (Vstart (cfg_start_id env)) in
let fct_in = add_node env (VfctIn (cfg_fct_in_id env)) in
let _ = add_edge env start Enone fct_in in
let fct_out = add_node env (VfctOut (cfg_fct_out_id env)) in
let exit = add_node env (Vexit (cfg_exit_id env)) in
let _ = add_edge env fct_out Enone exit in
env, fct_in, fct_out