Potential Gain/Loss Indicator

This indicator calculates the gains and losses in percentage based on the highest high (ATH) and lowest low (ATL) of a given period. It takes the period as an input parameter and calculates the ATH and ATL within that period.
The indicator then calculates the potential gains in percentage if the price goes back to the ATH, as well as the potential losses in percentage if the price goes back to the ATL.
A filled area chart is plotted to show the difference between gains and losses (gains - losses) using a stepline, with green color when positive and red color when negative. The coefficient parameter allows for adjusting the scale of the gains and losses.


# Parameters
1. `period` (integer): The period used for calculating the highest high (ATH) and lowest low (ATL) within the given range. The default value is 50, and the user can select any value greater than or equal to 1.
2. `coef` (float): A coefficient to adjust the scale of the gains and losses. The default value is 0.5, and the user can select any value greater than or equal to 0.1.