How to use the readdirp.bind function in readdirp

var logger = require('./logger.js');
logger.setLevel(opts.logLevel);
logger.info('Reading reports directory...');

var readOpts = {
  root: path.resolve(opts.reportsDirectory),
  fileFilter: '*.xml',
  entryType: 'files'
};

opts.fullOutputFilename = filenameHelpers.getOutputFilename(opts);

async.waterfall([

  readdirp.bind(readdirp, readOpts),

  function readFiles(results, next) {
    async.map(results.files, function(result, rnext) {
      fs.readFile(result.fullPath, function(err, filedata) {
        rnext(err, { name: result.name, data: filedata });
      });
    }, next);
  },

  function parseFiles(data, next) {
    async.map(data, function(result, pnext) {
      parseString(result.data, function(err, parsed) {
        if (opts.prependFilename)
          parsed.testsuites.filename = result.name;
        pnext(err, parsed);
      });