func FromHTTPContext() http.RequestFunc {
	return func(ctx context.Context, r *stdhttp.Request) context.Context {
		token, ok := ctx.Value(JWTTokenContextKey).(string)
		if ok {
			r.Header.Add("Authorization", generateAuthHeaderFromToken(token))
		}
		return ctx
	}
}
FromHTTPContext moves JWT token from context to request header. Particularly
useful for clients.
package jwt
import (
	"context"
	"fmt"
	stdhttp "net/http"
	"strings"
	"google.golang.org/grpc/metadata"
	"github.com/go-kit/kit/transport/grpc"
	"github.com/go-kit/kit/transport/http"
)
const (
	bearer       string = "bearer"
	bearerFormat string = "Bearer %s"
)
func ToHTTPContext() http.RequestFunc {
	return func(ctx context.Context, r *stdhttp.Request) context.Context {
		token, ok := extractTokenFromAuthHeader(r.Header.Get("Authorization"))
		if !ok {
			return ctx
		}
		return context.WithValue(ctx, JWTTokenContextKey, token)
	}
}