Module `Make.Parent`

Invariant is that parent is None in unattached mask and `Some` in the attached one. We can capture this with a GADT but there's some annoying issues with bin_io to do so

type t = ( Inputs.Base.t, string ) Core.Result.t

val t_of_sexp : Ppx_sexp_conv_lib.Sexp.t -> t

val sexp_of_t : t -> Ppx_sexp_conv_lib.Sexp.t