Goal:
    A : Type  j : positive  m1 : tree' A  a : A  m2 : tree' A  H : xH <> xO j
  ============================
   (get xH (Node (rem' j m1) (Some a) (Nodes m2)) = Some a)


DEBUG:Going to execute:
<coq-core.plugins.cc::cc@0> $1