Datetime

I hate programming with datetimes.

General resources

 * Python's  directives

Converting from int/float to datetime object
It depends on the timestamp item, specifically how long it is. For each thousands grouping it is past 10 digits, divide the original item by 1,000.

Excel
Assuming the data is in cell A1:

=(A1 / 24 / 60 / 60) + DATE(1970, 1, 1)