code: function verify(node, pattern, flags) {
              const patternNode = parser.parsePattern(
                  pattern,
                  0,
                  pattern.length,
                  flags.includes("u")
              );
              const has = {
                  surrogatePairWithoutUFlag: false,
                  combiningClass: false,
                  variationSelector: false,
                  emojiModifier: false,
                  regionalIndicatorSymbol: false,
                  zwj: false
              };
  
              visitRegExpAST(patternNode, {
                  onCharacterClassEnter(ccNode) {
                      for (const chars of iterateCharacterSequence(ccNode.elements)) {
                          for (const kind of kinds) {
                              has[kind] = has[kind] || hasCharacterSequence[kind](chars);
                          }
                      }
                  }
              });
  
              for (const kind of kinds) {
                  if (has[kind]) {
                      context.report({ node, messageId: kind });
                  }
              }
          }
docs: Verify a given regular expression.
  @param {Node} node The node to report.
  @param {string} pattern The regular expression pattern to verify.
  @param {string} flags The flags of the regular expression.
  @returns {void}