code: function emitWarning(msg, type) {
    if (process.emitWarning) {
      process.emitWarning(msg, type);
    } else {
      process.nextTick(function() {
        console.warn(type + ': ' + msg);
      });
    }
  }
docs: process.emitWarning or a polyfill
  @see https://nodejs.org/api/process.html#process_process_emitwarning_warning_options
  @ignore