How to use the expo-random.getRandomBytesAsync function in expo-random

let generateSecureRandom;
if (require.getModules) {
  const NativeModules = require('react-native').NativeModules;
  const RNSecureRandom = NativeModules.RNSecureRandom;
  const NativeUnimoduleProxy = NativeModules.NativeUnimoduleProxy;
  if (RNSecureRandom && RNSecureRandom.generateSecureRandomAsBase64) {
    generateSecureRandom = require('react-native-securerandom').generateSecureRandom;
  } else if (NativeUnimoduleProxy && NativeUnimoduleProxy.exportedMethods.ExpoRandom) {
    generateSecureRandom = require('expo-random').getRandomBytesAsync;
  }
}

if (!generateSecureRandom) {
  console.log(`
    isomorphic-webcrypto cannot ensure the security of some operations!
    Install and configure react-native-securerandom or expo-random
    If managed by Expo, run 'expo install expo-random'
  `);
  generateSecureRandom = function(length) {
    const uint8Array = new Uint8Array(length);
    while (length && length--) {
      uint8Array[length] = Math.floor(Math.random() * 256);
    }
    return Promise.resolve(uint8Array);
  }