anchor.diff:                      erlang:error(badarg, [T])
               end).
   -else.
  +-define(FORM_TEST(T), ok).
  +-define(EXPRS_TEST(T), ok).
   -define(TEST(T), ok).
   -endif.
   
  
positive.code:       Options :: options()).
  
  form(Thing, Options) ->
      ?TEST(Thing),
      State = state(Options),
      frmt(lform(Thing, options(Options)), State).
  
  
negative.code:       Options :: options()).
  
  exprs(Es, I, Options) ->
      ?EXPRS_TEST(Es),
      frmt({seq,[],[],[$,],lexprs(Es, options(Options))}, I, state(Options)).
  
  -spec(expr(Expression) -> io_lib:chars() when
  