+ let log_file_exists = std::path::Path::new(LOGFILENAME).exists();
+ let logfile = std::fs::OpenOptions::new()
+ .create_new(!log_file_exists)
+ .append(true)
+ .open(LOGFILENAME)
+ .expect("Coudln't open log file");
+ let mut log = csv::WriterBuilder::new()
+ .has_headers(!log_file_exists)
+ .from_writer(logfile);