Explain EXPLAIN QUERY TREE (children 2)
 Set
 SelectWithUnionQuery (children 1)
  ExpressionList (children 1)
   SelectQuery (children 2)
    ExpressionList (children 1)
     Function quantiles (children 2)
      ExpressionList (children 1)
       Function if (children 1)
        ExpressionList (children 3)
         Function modulo (children 1)
          ExpressionList (children 2)
           Identifier number
           Literal UInt64_2
         Identifier number
         Literal NULL
      ExpressionList (children 3)
       Literal Float64_0.5
       Literal Float64_0.9
       Literal Float64_0.99
    TablesInSelectQuery (children 1)
     TablesInSelectQueryElement (children 1)
      TableExpression (children 1)
       Function numbers (children 1)
        ExpressionList (children 1)
         Literal UInt64_100
