def ami_by_name(name, account_number)
      q = @ec2.images.with_owner(account_number).
          filter("name", name)
      return nil unless q.any?
      q.first
    end
def ami_by_name(name, account_number)
      q = @ec2.images.with_owner(account_number).
          filter("name", name)
      return nil unless q.any?
      q.first
    end
EC2 queries