code: def get_signer_hostname():
      
      region = os.getenv("AWS_REGION", "")
      region = region if region and region in SUPPORTED_REGIONS else "us-west-2"
      return "signer.{region}.iopipe.com".format(region=region)
docs: Returns the IOpipe signer hostname for a region
  
      :returns: The signer hostname
      :rtype str