code: function parsePaths(source, stylesheets, options) {
      return stylesheets.map((sheet) => {
          let sourceProtocol;
          const isLocalFile = sheet.substr(0, 5) === 'file:';
  
          if (sheet.substr(0, 4) === 'http') {
              /* No need to parse, it's already a valid path */
              return sheet;
          }
  
          /* Check if we are fetching over http(s) */
          if (isURL(source) && !isLocalFile) {
              sourceProtocol = url.parse(source).protocol;
  
              if (sheet.substr(0, 2) === '//') {
                  /* Use the same protocol we used for fetching this page.
                   * Default to http.
                   */
                  return sourceProtocol ? sourceProtocol + sheet : 'http:' + sheet;
              }
              return url.resolve(source, sheet);
          }
  
          /* We are fetching local files
           * Should probably report an error if we find an absolute path and
           *   have no htmlroot specified.
           */
          /* Fix the case when there is a query string or hash */
          sheet = sheet.split('?')[0].split('#')[0];
  
          /* Path already parsed by jsdom or user supplied local file */
          if (isLocalFile) {
              sheet = url.parse(sheet).path.replace('%20', ' ');
              /* If on windows, remove first '/' */
              sheet = isWindows() ? sheet.substring(1) : sheet;
  
              if (options.htmlroot) {
                  return path.join(options.htmlroot, sheet);
              }
              sheet = path.relative(path.join(path.dirname(source)), sheet);
          }
  
          if (sheet[0] === '/' && options.htmlroot) {
              return path.join(options.htmlroot, sheet);
          } else if (isHTML(source)) {
              return path.join(options.csspath, sheet);
          }
          return path.join(path.dirname(source), options.csspath, sheet);
      });
  }
docs: Parse paths relatives to a source.
  @param  {String} source      Where the paths originate from
  @param  {Array}  stylesheets List of paths
  @param  {Object} options     Options, as passed to UnCSS
  @return {Array}              List of paths