Notebook
## Timestamps Timestamps can be give as floating point number, strings, datatime objects. If only one timestamp is given the last value logged prior to the timestamp is given. If the second argument is 'next' the first value logged after the timestamp is given. If two timestamps are given the values logged in between (inclusively) are given. Timestamp are returned as unix timestamp (seconds and fraction from 1970-01-01 00:00:00 GMT) or optionally as datetime object.