Explain EXPLAIN SYNTAX (children 2)
 SelectWithUnionQuery (children 1)
  ExpressionList (children 1)
   SelectQuery (children 4)
    ExpressionList (children 3)
     Literal \'Get hierarchy\'
     Function toNullable (children 1)
      ExpressionList (children 1)
       Literal UInt64_13
     Function count (children 1)
      ExpressionList
    TablesInSelectQuery (children 1)
     TablesInSelectQueryElement (children 1)
      TableExpression (children 1)
       TableIdentifier dist_01247
    ExpressionList (children 1)
     Identifier number
    Set
 Identifier Null
