message: removing default paths in union example
diff: * This example reads two csv files and does a union on them.
  */
  int main(int argc, char *argv[]) {
  - std::string path1, path2;
  - if (argc != 3) {
  - path1 = "/tmp/csv1.csv";
  - path2 = "/tmp/csv2.csv";
  - } else {
  - path1 = argv[1];
  - path2 = argv[2];
  + if (argc < 3) {
  + LOG(ERROR) << "There should be two arguments with paths to csv files";
  + return 1;
  }
  auto start_time = std::chrono::steady_clock::now();
  @@ -39,16 +35,16 @@ int main(int argc, char *argv[]) {
  auto read_options = cylon::io::config::CSVReadOptions().UseThreads(false).BlockSize(1 << 30);
  // read first table
  - auto status = cylon::Table::FromCSV(ctx, path1, first_table, read_options);
  + auto status = cylon::Table::FromCSV(ctx, argv[1], first_table, read_options);
  if (!status.is_ok()) {
  - LOG(INFO) << "Table reading failed " << path1;
  + LOG(INFO) << "Table reading failed " << argv[1];
  ctx->Finalize();
  return 1;
  }
  // read second table
  - status = cylon::Table::FromCSV(ctx, path2, second_table, read_options);
  + status = cylon::Table::FromCSV(ctx, argv[2], second_table, read_options);
  if (!status.is_ok()) {
  - LOG(INFO) << "Table reading failed " << path2;
  + LOG(INFO) << "Table reading failed " << argv[2];
  ctx->Finalize();
  return 1;
  }
  