code: function(helperIsVisible) {
      var nodes = this._getAllNodesWithTag(this._doc, ["p", "pre"]);
  
      // Get <div> nodes which have <br> node(s) and append them into the `nodes` variable.
      // Some articles' DOM structures might look like
      // <div>
      //   Sentences<br>
      //   <br>
      //   Sentences<br>
      // </div>
      var brNodes = this._getAllNodesWithTag(this._doc, ["div > br"]);
      if (brNodes.length) {
        var set = new Set();
        [].forEach.call(brNodes, function(node) {
          set.add(node.parentNode);
        });
        nodes = [].concat.apply(Array.from(set), nodes);
      }
  
      // FIXME we should have a fallback for helperIsVisible, but this is
      // problematic because of jsdom's elem.style handling - see
      // https://github.com/mozilla/readability/pull/186 for context.
  
      var score = 0;
      // This is a little cheeky, we use the accumulator 'score' to decide what to return from
      // this callback:
      return this._someNode(nodes, function(node) {
        if (helperIsVisible && !helperIsVisible(node))
          return false;
        var matchString = node.className + " " + node.id;
  
        if (this.REGEXPS.unlikelyCandidates.test(matchString) &&
            !this.REGEXPS.okMaybeItsACandidate.test(matchString)) {
          return false;
        }
  
        if (node.matches && node.matches("li p")) {
          return false;
        }
  
        var textContentLength = node.textContent.trim().length;
        if (textContentLength < 140) {
          return false;
        }
  
        score += Math.sqrt(textContentLength - 140);
  
        if (score > 20) {
          return true;
        }
        return false;
      });
    }
docs: Decides whether or not the document is reader-able without parsing the whole thing.
  
  @return boolean Whether or not we suspect parse() will suceeed at returning an article object.