anchor.diff:      {match_context,0,Slots}.
   
   bsm_validate_context(Reg, Vst) ->
  -    bsm_get_context(Reg, Vst),
  +    _ = bsm_get_context(Reg, Vst),
       ok.
   
   bsm_get_context({x,X}=Reg, #vst{current=#st{x=Xs}}=_Vst) when is_integer(X) ->
  
positive.code: bsm_restore(Reg, {atom,start}, Vst) ->
      %% (Mostly) automatic save point refering to where the match started.
      %% It is always valid. But don't forget to validate the context register.
      bsm_get_context(Reg, Vst),
      Vst;
  bsm_restore(Reg, SavePoint, Vst) ->
      case bsm_get_context(Reg, Vst) of
  
negative.code:     call(send, 2, Vst);
  valfun_4({set_tuple_element,Src,Tuple,I}, Vst) ->
      assert_term(Src, Vst),
      assert_type({tuple_element,I+1}, Tuple, Vst),
      Vst;
  %% Match instructions.
  valfun_4({select_val,Src,{f,Fail},{list,Choices}}, Vst) ->
      assert_term(Src, Vst),
  