Time class with picosecond precision

[marcocod]

I'm looking for a class that is able to represent the time with the picosecond precision. I found the class numpy.datetime64 that can have this precision but the time span is only 212 days and I need at least 100 years. I could make my own class with a date that represent the year-month-day and an int for the picoseconds but, if available, I prefer to use something already done.
Thanks in advance for the help