Function download_and_find_checksum 

pub fn download_and_find_checksum(
    checksums_url: &str,
    filename: &str,
) -> Result<String>

Downloads a checksums file from checksums_url and extracts the expected hash for filename.

Supports the standard <hex_hash> <filename> format used by sha256sum / shasum, as well as single-hash files (one line containing only a hex hash).

Errors

• The checksums file download fails.
• The file cannot be read as UTF-8.
• No matching entry is found for filename.