>>> 1_234_567
1234567
>>>'{:_}'.format(123456789)
'123_456_789'
>>> '{:_}'.format(1234567)
'1_234_567'

The first example just shows how Python interprets a large number with underscores in it. The second example demonstrates that we can now give Python a string formatter, the “_” (underscore), in place of a comma. The results speak for themselves.

The numeric literals that include underscores behave the same way as normal numeric literals when doing calculations:

>>> 120_000 + 30_000
150000
>>> 120_000 - 30_000
90000

The Python documentation and the PEP also mention that you can use the underscores after any base specifier. Here are a couple of examples taken from the PEP and the documentation:

>>> flags = 0b_0011_1111_0100_1110
>>> flags
16206
>>> 0x_FF_FF_FF_FF
4294967295
>>> flags = int('0b_1111_0000', 2)
>>> flags
240

There are some notes about the underscore that need to be mentioned:

• You can only use one consecutive underscore and it has to be between digits and after any base specifier
• Leading and trailing underscores are not allowed

This is kind of a fun new feature in Python. While I personally don’t have any use cases for this in my current job, hopefully you will have one at yours.