code: function prev(index, lines) {
      while (index--) {
        var line = lines[index].trim();
  
        if (line && !/^(\/\/|\/\*)/.test(line)) {
          return { line: line, index: index };
        }
      }
  
      return {};
    }
docs: Find the previous line that contains content, ignoring whitespace and
  newlines.
  
  @param {Number} index
  @param {Array} lines
  @returns {Object}
  @api private