pub fn main(world: World) -> Void raises {
    let maybe_request: Maybe<String> = std.args.get(1)
    if !maybe_request.has {
        check world.err.write("usage: pass HTTP request envelope\n")
        return
    }
    let maybe_name: Maybe<String> = std.args.get(2)
    let net: Net = std.net.host()
    let client: HttpClient = std.http.client(net)
    var response: [512]u8 = [0_u8; 512]
    let result: HttpResult = std.http.fetch(client, std.mem.span(maybe_request.value), response, std.time.ms(5000))
    let len: usize = std.http.responseHeadersLen(response)
    if maybe_name.has {
        let value: HttpHeaderValue = std.http.headerValue(response, std.mem.span(maybe_name.value))
        let bytes: Maybe<Span<u8>> = std.http.headerBytes(response, value)
        if bytes.has && std.mem.len(bytes.value) > 0 {
            check world.out.write("http header found\n")
            return
        }
        check world.err.write("http header missing\n")
        return
    }
    if std.http.resultOk(result) && std.http.resultStatus(result) >= 200 && std.http.resultStatus(result) < 300 && len > 0 {
        check world.out.write("http headers ok\n")
        return
    }
    check world.err.write("http headers failed\n")
}