As a developer, diving in a new code base is not uncommon: you've just been hired, you change of project, you want to help an open source project, the open source library your project depends on is buggy, etc. It's like entering in a underwater cave, you don't know the treasures or the monsters you'll find there, neither if the path is treacherous or if it's a true labyrinth where you'll get lost. You can prepare yourself, you can plan your visit, you can equip yourself, you can survive and find the gem you're looking for...