code: function read(fp, opts) {
    if (opts && opts.read) {
      return opts.read(fp, opts);
    }
    return readData.call(this, fp, opts);
  }
docs: Default `read` function. Pass a function on `options.read`
  to customize.
  
  @param {String} `fp`
  @param {Object} `opts`
  @return {String}
  @api private