Add the ability to exclude files or directories for a scan

I'm doing some scans of projects and it would be nice to be able to avoid scanning directories with "tests" in the name or that start with "tests_*.py". Could we add an --exclude flag or perhaps the opposite approach, --include? Ideally it would take star expressions as well, so I could omit "tests_*.py" for example, or even just "tests*" would be great.