Function fetch 

pub async fn fetch(
    client: &Client,
) -> Result<(Vec<Server>, Option<ClientLocation>), Error>

Fetch the list of available speedtest servers, sorted by distance.

Also returns the client location if available, so callers don’t need to make a separate API call.

Errors

Returns Error::NetworkError if fetching the server list fails. Returns Error::DeserializeXml if the XML response cannot be parsed.