loadVariables() {
    return new Promise((resolve, reject) => {
      const checkpointLoader =
          new CheckpointLoader(GOOGLE_CLOUD_STORAGE_DIR + 'squeezenet1_1/');
      checkpointLoader.getAllVariables().then(variables => {
        this.variables = variables;
        resolve();
      });
    });
  }
Loads necessary variables for SqueezeNet. Resolves the promise when the
variables have all been loaded.