def has_roles?(*args)
      throw Exception.new("Must supply at least one role.") if args.empty?
      roles.where(name: args).count == args.count
    end
def has_roles?(*args)
      throw Exception.new("Must supply at least one role.") if args.empty?
      roles.where(name: args).count == args.count
    end
Determines if the user has all of the given roles linked to it.

 @param [String] args an argument list of one or more roles to check for.
 @return [true|false] true if the user is linked to all of the given roles.