SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 1)
   ExpressionList (children 1)
    Function age (children 1)
     ExpressionList (children 3)
      Literal \'nanosecond\'
      Function toDateTime64 (children 1)
       ExpressionList (children 3)
        Literal \'2015-08-18 20:30:36.100200005\'
        Literal UInt64_9
        Literal \'UTC\'
      Function toDateTime64 (children 1)
       ExpressionList (children 3)
        Literal \'2015-08-18 20:30:41.200400005\'
        Literal UInt64_9
        Literal \'UTC\'