Explain EXPLAIN SYNTAX (children 1)
 SelectWithUnionQuery (children 1)
  ExpressionList (children 1)
   SelectQuery (children 2)
    ExpressionList (children 1)
     Function multiIf (children 1)
      ExpressionList (children 3)
       Function equals (children 1)
        ExpressionList (children 2)
         Identifier number
         Literal UInt64_0
       Literal NULL
       Function toNullable (children 1)
        ExpressionList (children 1)
         Identifier number
    TablesInSelectQuery (children 1)
     TablesInSelectQueryElement (children 1)
      TableExpression (children 1)
       Function numbers (children 1)
        ExpressionList (children 1)
         Literal UInt64_10000