func GetSignerURL(region string) string {
	supportedRegions := map[string]struct{}{
		"ap-northeast-1": struct{}{},
		"ap-southeast-2": struct{}{},
		"eu-west-1":      struct{}{},
		"us-east-1":      struct{}{},
		"us-east-2":      struct{}{},
		"us-west-1":      struct{}{},
		"us-west-2":      struct{}{},
	}
	if region == "mock" {
		return os.Getenv("MOCK_SERVER")
	}
	if _, exists := supportedRegions[region]; exists {
		return fmt.Sprintf("https://signer.%s.iopipe.com/", region)
	}
	return "https://signer.us-west-2.iopipe.com/"
}
GetSignerURL returns the URL for the signer in the specified region
package iopipe
import (
	"bytes"
	"encoding/json"
	"fmt"
	"io/ioutil"
	"net/http"
	"os"
	"time"
)
type SignerRequest struct {
	ARN       string `json:"arn"`
	RequestID string `json:"requestId"`
	Timestamp int    `json:"timestamp"`
	Extension string `json:"extension"`
}
type SignerResponse struct {
	JWTAccess     string `json:"jwtAccess"`
	SignedRequest string `json:"signedRequest"`
	URL           string `json:"url"`
}