Generate bson object ids with a specific time in python

gen_bson_oid.py

"""
Use to generate an oid in python with a specific time, but also including uniqueness.
Helpful for generating ids for data for old time periods for testing.

The 3 bytes for machine id and the 2 bytes for process id are zeroed out.
You need to update the value of `inc` to ensure you generate unique ids within a single second.

See the `_generate` method on the ObjectId class for more details:
https://github.com/mongodb/mongo-python-driver/blob/3.5.1/bson/objectid.py#L165
"""

import binascii
import calendar
import datetime
import struct

dt = datetime.datetime(2015, 6, 15)
inc = 1

# Saves the value as a string
oid = binascii.hexlify(struct.pack(">i", int(calendar.timegm(dt.timetuple()))) + b"\x00\x00\x00\x00\x00" + struct.pack(">i", inc % 0xFFFFFF)[1:4])