Explain EXPLAIN QUERY TREE (children 1)
 SelectWithUnionQuery (children 1)
  ExpressionList (children 1)
   SelectQuery (children 2)
    ExpressionList (children 1)
     Function uniq (children 1)
      ExpressionList (children 1)
       Function toString (children 1)
        ExpressionList (children 1)
         Function abs (children 1)
          ExpressionList (children 1)
           Function materialize (children 1)
            ExpressionList (children 1)
             Identifier number
    TablesInSelectQuery (children 1)
     TablesInSelectQueryElement (children 1)
      TableExpression (children 1)
       Function numbers (children 1)
        ExpressionList (children 1)
         Literal UInt64_10
