fact: Definition fillLocation (e:E) (l:location) : tree := match l with | TwoHole_l tl tr c => zip (Two_t tl e tr) c | ThreeLeftHole_l tl tm vr tr c => zip (Three_t tl e tm vr tr) c | ThreeRightHole_l tl el tm tr c => zip (Three_t tl el tm e tr) c end.
imports: ExtLib.Structures.Monads ExtLib.Data.Monads.OptionMonad ExtLib.Programming.Extras