code: function(doc) {
    // Heuristic for the custom docs in the lib/selenium-webdriver/ folder.
    if (doc.name && doc.name.startsWith('webdriver')) {
      return;
    }
    var template = _.template('https://github.com/angular/protractor/blob/' +
        '<%= linksHash %>/lib/<%= fileName %>.ts');
  
    doc.sourceLink = template({
      linksHash: linksHash,
      fileName: doc.fileName
    });
  }
docs: Add a link to the source code.
  @param {!Object} doc Current document.