High & Low Of Custom Session

This script boxes a custom session and sets the box at the high and low of the session and draws that box to the next session.
Box color is determined by price in relation to the box position. Box color is set at the start of the next session. This allows
user to lookback at multiple box sets to see how each day closed in relation to the session highlighted.

I have written this for backtesting purposes and intend to expand it to use with volume analysis and gradient color to change the box color based on how many times price tests
the box.