\def-lazy(_if1_ 2 $0)\
\def-lazy(_if0_ 2 $1)\
\def-lazy(if 3 \({_if$0_} $1 $2))\
\if(0 a {b\(if 1 c d)})
\def(x 1 \(if $0 0 1))\
\if(\x(1) y z)