Goal:
  
  G : t
  HI : invariants
  HG : acyclic_no_loop
  x : V.t
  z : Z
  h : lsp x (s G) = Some z
  x0 : SPath (V G) x (s G)
  H : sweight x0 = z
  H0 : sweight x0 <= 0
  ============================
   (z <= 0)


DEBUG:Going to execute:
fun => <coq-core.plugins.zify::ITER@0>