Part $1$: Beta Calculation $(14$ points$)$

In finance, Beta is a measure of the systematic risk of a security or portfolio compared to the market as a whole. Please follow the instruction below to calculate the Beta of Netflix, Inc.

Step $1(6$ points$)$

Read file NFLX$.$csv to create DataFrame NFLX

Create variable Close$\_$Lag as the lag$(1)$ of "Adj Close"

Generate variable Return$\_$NFLX as the ratio of $("$Adj Close" $-$ "Close$\_$Lag"$)/$ "Close$\_$Lag"

Keep only the variables Date and Return$\_$NFLX in DataFrame NFLX