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(*  v      *   The Coq Proof Assistant  /  The Coq Development Team     *)
(* <O___,, *   INRIA - CNRS - LIX - LRI - PPS - Copyright 1999-2016     *)
(*   \VV/  **************************************************************)
(*    //   *      This file is distributed under the terms of the       *)
(*         *       GNU Lesser General Public License Version 2.1        *)
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(** [start_deriving f suchthat lemma] starts a proof of [suchthat]
    (which can contain references to [f]) in the context extended by
    [f:=?x]. When the proof ends, [f] is defined as the value of [?x]
    and [lemma] as the proof. *)
val start_deriving : Names.Id.t -> Constrexpr.constr_expr -> Names.Id.t -> unit