docs: protected AstNode parseAlterStatement( DdlTokenStream tokens,
                                             AstNode parentNode ) throws ParsingException {
          assert tokens != null;
          assert parentNode != null;
  
          if (tokens.matches(ALTER, TABLE)) {
              return parseAlterTableStatement(tokens, parentNode);
          } else if (tokens.matches("ALTER", "DOMAIN")) {
              markStartOfStatement(tokens);
              tokens.consume("ALTER", "DOMAIN");
              String domainName = parseName(tokens);
              AstNode alterNode = nodeFactory().node(domainName, parentNode, TYPE_ALTER_DOMAIN_STATEMENT);
              parseUntilTerminator(tokens);
              markEndOfStatement(tokens, alterNode);
              return alterNode;
          }
          return null;
      }