use rustc::hir::def_id::DefId;
use rustc::hir::Node;
use rustc::middle::region;
use rustc::infer::InferCtxt;
use rustc::ty::subst::Subst;
use rustc::ty::{self, Ty, TyCtxt};
use rustc::hir::def_id::DefId;
use rustc::hir::Node;
use rustc::middle::region;
use rustc::infer::InferCtxt;
use rustc::ty::subst::Subst;
use rustc::ty::{self, Ty, TyCtxt};