get_tweets.RdFunction to get tweets from time slots
get_tweets(my_day, start_time, end_time)
| my_day | day of the conference, in format e.g. `2019-07-24` |
|---|---|
| start_time | start time of the talk, e.g. HH:MM |
| end_time | end time of the talk, e.g. HH:MM |
DT datatable of tweets