`explain` always true when invoked from commandline

[tomsilver]

Looking here:

parser.add_argument('--explain', default=True, action='store_true', help='explain')

Since default=True, args.explain will always be True, I think, even if --explain is not given.

I noticed this because of a discrepancy between running popper from the command line vs. running from another python program. The former was much faster than the latter, and it was because explain was true in the former but not the latter.

Btw, what does explain mean?

[andrewcropper]

fixed by enabling explain by default 1c69be1

the explain setting tells Popper to find the minimal unsatisfiable core of a totally incomplete program (a program that does not cover any positive examples)