Python: Use underscores as visual separators for numbers

Python 3.6 introduced (via PEP 515) the use of underscores as visual separators for numbers, in order to:

aid readability of long literals, or literals whose value should clearly separate into parts, such as bytes or words in hexadecimal notation.

Examples:

# grouping decimal numbers by thousands
amount = 10_000_000.0

# grouping hexadecimal addresses by words
addr = 0xCAFE_F00D

# grouping bits into nibbles in a binary literal
flags = 0b_0011_1111_0100_1110

# same, for string conversions
flags = int('0b_1111_0000', 2)

Via Dan Maftei.