// Copyright 2019 The Go Authors. All rights reserved.// Use of this source code is governed by a BSD-style// license that can be found in the LICENSE file.// Package xerrors implements functions to manipulate errors.//// This package is based on the Go 2 proposal for error values:// https://golang.org/design/29934-error-values//// These functions were incorporated into the standard library's errors package// in Go 1.13:// - Is// - As// - Unwrap//// Also, Errorf's %w verb was incorporated into fmt.Errorf.//// Use this package to get equivalent behavior in all supported Go versions.//// No other features of this package were included in Go 1.13, and at present// there are no plans to include any of them.packagexerrors// import "golang.org/x/xerrors"