@gen = (?(((a a) @gen__C0) b) b)
@gen__C0 = ({a d} ({$([*2] $([+1] b)) $([*2] e)} (c f)))
&! @gen ~ (a (b c))
&! @gen ~ (d (e f))
@main = a
& @sum ~ (20 (@main__C0 a))
@main__C0 = a
& @gen ~ (20 (0 a))
@sum = (?(((* 1) @sum__C0) a) a)
@sum__C0 = ({a c} ((b d) f))
&! @sum ~ (a (b $([+] $(e f))))
&! @sum ~ (c (d e))