Not to sound dismissive, but virtually everyone, who knows what are regular expressions, knows this. Only last, 15th, lesson starts to touch on things that are

Not to sound dismissive, but virtually everyone, who knows what are regular expressions, knows this. Only last, 15th, lesson starts to touch on things that are arguably not common knowledge - word boundaries and back references. Look aheads and look behinds, the parts which most people struggle with, aren't covered at all.