Lab, sigma, and big pi:
	Summation:  Capital sigma, add up all the numbers
	Product:  Capital pi, multiply all the numbers together
	Couple examples on the board

Anyway, it's a different way to express a loop
	Convert, again on board

Second note:  vulkan tutorial was slow
	Let's pretend we don't have an RTX 2080 and do this on the CPU...

Interfaces:
	A collection of functions that can be applied to a data type
	Some languages (Java, C++ with MFC) support these
	Python implicitly does, but not by name
	Linux kernel uses these by idea, but not name
	Matching:
		Java, C++, Python:  Match by name (call a named method on the type)
		C:  Function pointers (a struct is populated with function pointers)
	Important point here:  An object can support more than one interface!	
	Principle here:  A wall tile is a game object, and ALSO a block object
		Maybe a block object isn't really part of the game, just landscaping or whatnot
		Some game objects don't actually block player movement
		Some objects do both!

C++ support for the concept of interfaces is via inheritance:
	An object can inherit charactaristics from a base object
	Can add more properties or methods
	Can use different method definitions
	Must support (by name and parameters) the same methods
		NOT by definition - this can be different
		Same prototype, different definition
	
Sometimes the base class isn't intended to ever be made
	Essentially, it defines an interface
	As in, objects of this type must have these methods and these properties
		Rigidly-enforced by the compiler
		"A mouse must have at least two movement axis and at least one button"
		"A three-button wheelmouse must have at least 4 movement axis and three buttons"
		Implementation might vary quite a bit!
	There isn't really any completely generic car, yet standards for cars exist

Most of the time, you can just address objects as though they're generic
	What if you needed to know what specific type of object it is?
		Field with a definition?
		This may indicate an architecture problem (game engine example)