SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 1)
   ExpressionList (children 2)
    Literal \'constants:\'
    Function array (children 1)
     ExpressionList (children 4)
      Function tuple (children 1)
       ExpressionList (children 2)
        Literal NULL
        Function array (children 1)
         ExpressionList
      Function tuple (children 1)
       ExpressionList (children 2)
        Function toNullable (children 1)
         ExpressionList (children 1)
          Function toFixedString (children 1)
           ExpressionList (children 2)
            Literal \'a\'
            Literal UInt64_4
        Function array (children 1)
         ExpressionList
      Function tuple (children 1)
       ExpressionList (children 2)
        Function toNullable (children 1)
         ExpressionList (children 1)
          Function toFixedString (children 1)
           ExpressionList (children 2)
            Literal \'a\'
            Literal UInt64_4
        Function array (children 1)
         ExpressionList (children 1)
          Function tuple (children 1)
           ExpressionList (children 2)
            Literal NULL
            Literal \'a\'
      Function tuple (children 1)
       ExpressionList (children 2)
        Function toNullable (children 1)
         ExpressionList (children 1)
          Function toFixedString (children 1)
           ExpressionList (children 2)
            Literal \'a\'
            Literal UInt64_4
        Function array (children 1)
         ExpressionList (children 2)
          Function tuple (children 1)
           ExpressionList (children 2)
            Literal NULL
            Literal \'a\'
          Function tuple (children 1)
           ExpressionList (children 2)
            Literal NULL
            Literal \'a\'
