Maybe there's a gap in my knowledge of notation, but I was confused by:
> Let’s define the Lagrange basis functions
It looks like you defined `l_i(x)` as a piecewise function or a step function.
But then you show with it's actual definition later in that section. (That's what that section is building to and explaining.)
Thank you for the feedback. The idea was to first define what we want the basis functions to be (a pretty abstract definition) and then develop how to actually get that from _normal_, continuous functions.