@Nullable private static BinaryContext pushContext(BinaryContext ctx){
  BinaryContext old=BINARY_CTX.get();
  BINARY_CTX.set(ctx);
  return old;
}

@ Nullable private static BinaryContext pushContext ( BinaryContext ctx ) { BinaryContext old = BINARY_CTX . get ( ) ; BINARY_CTX . set ( ctx ) ; return old ; }
push binary context and return the old one .
