fact: Definition firstS : forall (block:BLOCK.t), {s:STATEMENT.t | head (statements block) = Some s}+{statements block=nil}.
imports: JML(JMLProgramPlus) Coq(ZArith) JML(ZHelpers) JML(LogicHelpers) Coq(Bool) Coq(Sumbool) Coq(Ndec) JML(PosAux) JML(EqBoolAux) Coq(Relation_Operators) Coq(List) JML(ListFunctions) JML(ListHelpers) JML(OptionHelpers)