code: function askRegion() {
      if (this.abort) return null;
      const done = this.async();
      const prompts = [
          {
              type: 'list',
              name: 'region',
              message: 'Which region?',
              choices: regionList,
              default: this.aws.region ? _.indexOf(regionList, this.aws.region) : this.awsFacts.defaultRegion
          }
      ];
  
      return this.prompt(prompts).then(props => {
          const region = props.region;
          if (region) {
              this.aws.region = region;
              done();
          } else {
              this.abort = true;
              done();
          }
      });
  }
docs: Ask user what type of Region is to be created?