# A tibble: 12 x 2
                    x         y
               <time>    <time>
1 2016-01-01 12:34:57 <POSIXlt>
2 2016-01-01 12:34:58 <POSIXlt>
3 2016-01-01 12:34:59 <POSIXlt>
4 2016-01-01 12:35:00 <POSIXlt>
5 2016-01-01 12:35:01 <POSIXlt>
6 2016-01-01 12:35:02 <POSIXlt>
7 2016-01-01 12:35:03 <POSIXlt>
8 2016-01-01 12:35:04 <POSIXlt>
# ... with 4 more rows
