docs: function copyRegExp(regExpArg, options) {
              var flags;
  
              if (!isPlainObject(options)) {
                  options = {};
              }
  
              // Get native flags in use
              flags = onlyCoercibleToString(pExec.call(getNativeFlags, $toString(regExpArg))[1]);
              if (options.add) {
                  flags = pReplace.call(flags + options.add, clipDups, '');
              }
  
              if (options.remove) {
                  // Would need to escape `options.remove` if this was public
                  flags = pReplace.call(flags, new CRegExp('[' + options.remove + ']+', 'g'), '');
              }
  
              return new CRegExp(regExpArg.source, flags);
          }