It's all well and fine if all that you see is what will run. These days so many frameworks and layers are below and on top of your code that it's hard to know

It's all well and fine if all that you see is what will run. These days so many frameworks and layers are below and on top of your code that it's hard to know how your (relatively) simple code will behave at runtime. We've become on some level config and package install warriors.