docs: function findSourceInLine(fragment, url, line) {
          var source = getSource(url),
              re = new RegExp('\\b' + escapeRegExp(fragment) + '\\b'),
              m;
  
          line -= 1;
  
          if (source && source.length > line && (m = re.exec(source[line]))) {
              return m.index;
          }
  
          return null;
      }