sig
val as_eqn : Literal.t -> (Literal.term * Literal.term * bool) option
val get_eqn :
Literal.t ->
Libzipperposition.Position.t ->
(Literal.term * Literal.term * bool) option
val get_arith : Literal.t -> ArithLit.t option
val focus_arith :
Literal.t -> Libzipperposition.Position.t -> ArithLit.Focus.t option
val unfocus_arith : ArithLit.Focus.t -> Literal.t
end