The default implementation used by ConfigParser. It enables values to contain format strings which refer to other values in the same section, or values in the special default section [1]. Additional default values can be provided on initialization.
class configparser.BasicInterpolation[Paths]
home_dir: /Users
my_dir: %(home_dir)s/lumberjack
my_pictures: %(my_dir)s/Pictures
[Escape]
use a %% to escape the % sign (% is the only character that needs to be escaped):
gain: 80%%