val at : t -> Position.t -> termReturn the subterm at the given position, or
Invalid_argument if the position is not valid
val lit_at : t -> Position.t -> Literal.t * Position.tLookup which literal the position is about, return it and the rest of the position.
Invalid_argument if the position is not valid
val replace : t -> at:Position.t -> by:term -> unitIn-place modification of the array, in which the subterm at given position is replaced by the by term.
Invalid_argument if the position is not valid
val idx : Position.t -> intIndex in the literal array
Invalid_argument if the position is incorrect
val tail : Position.t -> Position.tsub-position
Invalid_argument if the position is incorrect
val cut : Position.t -> int * Position.tIndex + literal position