Explain EXPLAIN AST (children 2)
 Set
 SelectWithUnionQuery (children 1)
  ExpressionList (children 1)
   SelectQuery (children 2)
    ExpressionList (children 1)
     Literal UInt64_1
    TablesInSelectQuery (children 3)
     TablesInSelectQueryElement (children 1)
      TableExpression (children 1)
       TableIdentifier t0
     TablesInSelectQueryElement (children 2)
      TableExpression (children 1)
       TableIdentifier t0 (alias tx)
      TableJoin (children 1)
       Function isNotDistinctFrom (children 1)
        ExpressionList (children 2)
         Identifier t0.c0
         Identifier tx.c0
     TablesInSelectQueryElement (children 2)
      TableExpression (children 1)
       TableIdentifier t0 (alias ty)
      TableJoin
