private static void RevokeSign()
{
Console.WriteLine();
Guid petitionGuid = GetPetitionGuid();
Console.WriteLine();
Console.Write("Email: ");
var email = Console.ReadLine();
_service.RevokeSign(petitionGuid, email);
Console.WriteLine("Petition sign revoked!");
Console.WriteLine("Press any key to return to the menu...");
Console.ReadKey();
}