docs: function listSubnets(vpcId) {
      const params = {
          Filters: [
              {
                  Name: 'vpc-id',
                  Values: [vpcId]
              },
              {
                  Name: 'state',
                  Values: ['available']
              }
          ]
      };
      return spinner(
          ec2
              .describeSubnets(params)
              .promise()
              .then(data => data.Subnets)
      );
  }