Explain EXPLAIN AST (children 1)
 SelectWithUnionQuery (children 1)
  ExpressionList (children 1)
   SelectQuery (children 1)
    ExpressionList (children 1)
     Function isNotDistinctFrom (children 1)
      ExpressionList (children 2)
       Literal UInt64_1
       Function plus (children 1)
        ExpressionList (children 2)
         Literal UInt64_1
         Literal UInt64_1
