SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 1)
   ExpressionList (children 1)
    Function flatten (children 1)
     ExpressionList (children 1)
      Function arrayJoin (children 1)
       ExpressionList (children 1)
        Literal Array_[Array_[Array_[UInt64_1, UInt64_2, UInt64_3], Array_[UInt64_4, UInt64_5]], Array_[Array_[UInt64_6], Array_[UInt64_7, UInt64_8]]]