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