Explain EXPLAIN (children 2)
 Set
 SelectWithUnionQuery (children 1)
  ExpressionList (children 1)
   SelectQuery (children 4)
    ExpressionList (children 1)
     Asterisk
    TablesInSelectQuery (children 1)
     TablesInSelectQueryElement (children 1)
      TableExpression (children 1)
       TableIdentifier t1
    Function or (children 1)
     ExpressionList (children 2)
      Function greater (children 1)
       ExpressionList (children 2)
        Identifier x
        Literal UInt64_2
      Function equals (children 1)
       ExpressionList (children 2)
        Identifier y
        Literal \'a\'
    Literal UInt64_10
