anchor.diff:      : ALIAS | ANALYZER | BERNOULLI | BLOB | CATALOGS | CHAR_FILTERS | CLUSTERED
       | COLUMNS | COPY | CURRENT | DATE | DAY | DISTRIBUTED | DUPLICATE | DYNAMIC | EXPLAIN
       | EXTENDS | FOLLOWING | FORMAT | FULLTEXT | FUNCTIONS | GEO_POINT | GLOBAL
  -    | GRAPHVIZ | HOUR | IGNORED | INTERVAL | KEY | KILL | LOGICAL | MATERIALIZED | MINUTE
  +    | GRAPHVIZ | HOUR | IGNORED | KEY | KILL | LOGICAL | MATERIALIZED | MINUTE
       | MONTH | OFF | ONLY | OVER | PARTITION | PARTITIONED | PARTITIONS | PLAIN
       | PRECEDING | RANGE | REFRESH | ROW | ROWS | SCHEMAS | SECOND
       | SHARDS | SHOW | STRICT | SYSTEM | TABLES | TABLESAMPLE | TEXT | TIME
  
positive.code: FOR: 'FOR';
  DATE: 'DATE';
  TIME: 'TIME';
  INTERVAL: 'INTERVAL';
  YEAR: 'YEAR';
  MONTH: 'MONTH';
  DAY: 'DAY';
  
negative.code: simpleExpr
      : NULL
      | (dateValue) => dateValue
      | ('[') => arrayLiteral
      | ('{') => objectLiteral
      | qnameOrFunction
  