anchor.diff:  %% defprotocol
   %%------------------------------------------------------------------------------
   ast(#{op := defprotocol} = Expr, State) ->
  +  ?DEBUG(defprotocol),
     #{ name         := NameSym
      , methods_sigs := MethodsSigs
      , env          := Env
  
positive.code: 
    push_ast(Ast, State);
  ast(#{op := invoke} = Expr, State) ->
    #{ args := ArgsExpr
     , f    := FExpr
     , env  := Env
  
negative.code: %% on_load
  %%------------------------------------------------------------------------------
  ast(#{op := on_load} = Expr, State) ->
    ?DEBUG(on_load),
    #{ body := BodyExpr
     , env  := Env
     } = Expr,
  