Explain EXPLAIN SYNTAX (children 1)
 SelectWithUnionQuery (children 1)
  ExpressionList (children 1)
   SelectQuery (children 1)
    ExpressionList (children 5)
     Function count (children 1)
      ExpressionList
     Function count (children 1)
      ExpressionList (children 1)
       Literal UInt64_1
     Function count (children 1)
      ExpressionList (children 1)
       Literal Int64_-1
     Function sum (children 1)
      ExpressionList (children 1)
       Literal UInt64_1
     Function count (children 1)
      ExpressionList (children 1)
       Literal NULL
