parsing NetKAT polcies and predicates
val pol_of_string : ?pos:Lexing.position ‑> string ‑> Syntax.policy
val pred_of_string : ?pos:Lexing.position ‑> string ‑> Syntax.pred
val pol_of_file : string ‑> Syntax.policy
val pred_of_file : string ‑> Syntax.pred
module Portless : sig ... end