Request.Messagemodule Tool_call : sig ... endmodule Content_part : sig ... endmodule Content : sig ... endtype t = {role : string;content : Content.t option;tool_calls : Tool_call.t list;tool_call_id : string option;}val sexp_of_t : t -> Sexplib0.Sexp.tval user : string -> tval user_multipart : Content_part.t list -> tval system : string -> tval assistant : ?content:string -> ?tool_calls:Tool_call.t list -> unit -> tval tool : tool_call_id:string -> content:string -> t