Explain EXPLAIN AST (children 1)
 SelectWithUnionQuery (children 1)
  ExpressionList (children 1)
   SelectQuery (children 1)
    ExpressionList (children 1)
     Function not (children 1)
      ExpressionList (children 1)
       Function isNotDistinctFrom (children 1)
        ExpressionList (children 2)
         Literal UInt64_1
         Literal UInt64_1
