(
a
*
{-{/ {-{ /x }-} }-}
(| (/ p q) {-{ /y }-})
{-{/ (| x y)}-}
(/ a (| b c))
(/ 
  a 
  (desc
    b 
    (filt c {-{desc (| x (| y x))}-})
  ) 
)
{-{ / t }-}
)