def METHOD_NAME(self):
    # Billing file name, generated by Amazon itself
    # Format : 123456789012-aws-billing-csv-yyyy-mm.csv
    s3_file_key = "{}-aws-billing-csv-{}-{}.csv".format(
        self.aws_account_id,
        datetime.datetime.now().strftime("%Y"),
        datetime.datetime.now().strftime("%m"),
    )
    i = 0
    # Connection to s3 service
    try:
        conn = boto.connect_s3(self.aws_access_key_id, self.aws_secret_access_key)
    except:  # noqa e722
        return "conn_error"
    # Connection to the bucket
    try:
        bucket = conn.get_bucket(self.s3_bucket_name)
    except:  # noqa e722
        return "bucket_error"
    # Fetch the objects keys and get the billing file
    try:
        k = Key(bucket)
        k.key = s3_file_key
        k.get_contents_to_filename(self.billing_file)
        k.close
    except:  # noqa e722
        return "key_error"
    # Parse the file and get the InvoiceTotal amount
    try:
        with Path(self.billing_file).open("rb") as f:
            reader = csv.reader(f)
            for row in reader:
                if "".join(row).find("InvoiceTotal") == -1:
                    continue
                i = i + 1
                return row[-1]
    except:  # noqa e722
        return "csv_error"
    return False