Explain EXPLAIN SYNTAX (children 1) SelectWithUnionQuery (children 1) ExpressionList (children 1) SelectQuery (children 2) ExpressionList (children 1) Function uniqTheta (children 1) ExpressionList (children 1) Function bitNot (children 1) ExpressionList (children 1) Identifier x TablesInSelectQuery (children 1) TablesInSelectQueryElement (children 1) TableExpression (children 1) Subquery (children 1) SelectWithUnionQuery (children 1) ExpressionList (children 1) SelectQuery (children 2) ExpressionList (children 1) Function modulo (alias x) (children 1) ExpressionList (children 2) Identifier number Literal UInt64_2 TablesInSelectQuery (children 1) TablesInSelectQueryElement (children 1) TableExpression (children 1) Function numbers (children 1) ExpressionList (children 1) Literal UInt64_10