The biggest issue I have is with this step: > - We're going to take that and add it all together Here, we have an imaginary variable: namely, "that." Somethin

The biggest issue I have is with this step: > - We're going to take that and add it all together Here, we have an imaginary variable: namely, "that." Something that we need to keep track of and is not explicitly referenced anywhere. It's relatively easy when you only have one of these things, but with complex map-reducer logic, you can end up having a whole bunch of these. In the for-loop, everything I use is explicitly referenced. There's no "that" -- everything is "r" or "x" or "j."