async function loadHostedData(url, numClasses) {
  ui.status('Loading data from ' + url);
  try {
    const raw = await fetch(url);
    const data = await raw.json();
    const result = util.convertDataToTensors(data, numClasses);
    result['data'] = data;
    ui.status('Done loading data.');
    return result;
  } catch (err) {
    console.error(err);
    ui.status('Loading data failed.');
  }
}
Load data file stored at a remote URL.

@return An object containing metadata as key-value pairs.