Fetch Previous Day's Data:
Uses request.security to get the previous day's high, low, and close prices.
lookahead=barmerge.lookahead_on ensures the data fetched is fixed for the current session.
Calculate CPR Levels:
Pivot: Average of the previous day's high, low, and close.
Bottom Central Pivot (BC): Average of the previous day's high and low.
Top Central Pivot (TC): Derived from the pivot and BC.
R1 and S1: First resistance and support levels calculated from the pivot and previous day's prices.
Plotting:
Plots the CPR levels (pivot, BC, TC, R1, S1) on the chart with different colors.