text: // Copyright 2019 Google LLC
  //
  // Licensed under the Apache License, Version 2.0 (the "License");
  // you may not use this file except in compliance with the License.
  // You may obtain a copy of the License at
  //
  //     https://www.apache.org/licenses/LICENSE-2.0
  //
  // Unless required by applicable law or agreed to in writing, software
  // distributed under the License is distributed on an "AS IS" BASIS,
  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  // See the License for the specific language governing permissions and
  // limitations under the License.
  
  // Code generated by gapic-generator. DO NOT EDIT.
  
  // Package trace is an auto-generated package for the
  // Stackdriver Trace API.
  //
  //   NOTE: This package is in alpha. It is not stable, and is likely to change.
  //
  // Sends application trace data to Stackdriver Trace for viewing. Trace data
  // is
  // collected for all App Engine applications by default. Trace data from
  // other
  // applications can be provided using this API.
  //
  // Use of Context
  //
  // The ctx passed to NewClient is used for authentication requests and
  // for creating the underlying connection, but is not used for subsequent calls.
  // Individual methods on the client use the ctx given to them.
  //
  // To close the open connection, use the Close() method.
  //
  // For information about setting deadlines, reusing contexts, and more
  // please visit godoc.org/cloud.google.com/go.
  package trace // import "cloud.google.com/go/trace/apiv2"
  
  import (
  	"context"
  	"runtime"
  	"strings"
  	"unicode"
  
  	"google.golang.org/grpc/metadata"
  )
  
  func insertMetadata(ctx context.Context, mds ...metadata.MD) context.Context {
  	out, _ := metadata.FromOutgoingContext(ctx)
  	out = out.Copy()
  	for _, md := range mds {
  		for k, v := range md {
  			out[k] = append(out[k], v...)
  		}
  	}
  	return metadata.NewOutgoingContext(ctx, out)
  }
  
  // DefaultAuthScopes reports the default set of authentication scopes to use with this package.
  func DefaultAuthScopes() []string {
  	return []string{
  		"https://www.googleapis.com/auth/cloud-platform",
  		"https://www.googleapis.com/auth/trace.append",
  	}
  }
  
  // versionGo returns the Go runtime version. The returned string
  // has no whitespace, suitable for reporting in header.
  func versionGo() string {
  	const develPrefix = "devel +"
  
  	s := runtime.Version()
  	if strings.HasPrefix(s, develPrefix) {
  		s = s[len(develPrefix):]
  		if p := strings.IndexFunc(s, unicode.IsSpace); p >= 0 {
  			s = s[:p]
  		}
  		return s
  	}
  
  	notSemverRune := func(r rune) bool {
  		return strings.IndexRune("0123456789.", r) < 0
  	}
  
  	if strings.HasPrefix(s, "go1") {
  		s = s[2:]
  		var prerelease string
  		if p := strings.IndexFunc(s, notSemverRune); p >= 0 {
  			s, prerelease = s[:p], s[p:]
  		}
  		if strings.HasSuffix(s, ".") {
  			s += "0"
  		} else if strings.Count(s, ".") < 2 {
  			s += ".0"
  		}
  		if prerelease != "" {
  			s += "-" + prerelease
  		}
  		return s
  	}
  	return "UNKNOWN"
  }
  
  const versionClient = "20190716"
  