def archive_url(cik: Union[str, int], accession_number: Union[str, int]) -> str:
    """
    Builds the archive URL for the SEC accession number. Looks for the .txt file for the
    filing, while follows a {accession_number}.txt format.
    """
    filename = f"{_add_dashes(accession_number)}.txt"
    accession_number = _drop_dashes(accession_number)
    return f"{SEC_ARCHIVE_URL}/{cik}/{accession_number}/{filename}"

    Builds the archive URL for the SEC accession number. Looks for the .txt file for the
    filing, while follows a {accession_number}.txt format.
    
llama-index-integrations/readers/llama-index-readers-sec-filings/llama_index/readers/sec_filings/prepline_sec_filings/fetch.py