Here is the text 

https://docs.python.org/3.6/distutils/apiref.html#distutils.util.strtobool

Convert a string representation of truth to true (1) or false (0).

True values are y, yes, t, true, on and 1; false values are n, no, f, false, off and 0. Raises ValueError if val is anything else.

I wondered what would happen with 'FALSE' i.e. upper case. It appears to behave the same way as 'false'. In fact case does not seem to be an issue, so 'FaLsE' will return 0 as well.

So a note that this function is independent of case may be helpful