ssj questions

• what exactly is program stack's growth direction?
• why property in prototype of an object can not modified by object?
• Why can traits in scala.collection create an instance?
• when will main thread exit in python
• how does it happened that a variable used before it's declared?
• How to avoid write code like "XXX!=null" or "XXX!=null || XXX.isEmpty" [duplicate]
• Internal mechanism of sizeof in C?
• What is unicode_literals used for?

ssj answers