DB<5> p B::Deparse->new()->coderef2text( sub{!!1} )
{
    use feature ... ; # shortened
    !0;
}
  DB<6> p B::Deparse->new()->coderef2text( sub{!!0} )
{
    use feature ... ; # yadda
    !1;
}
  DB<7> p $]
5.038002