Williams Accumulation/Distribution (Williams AD) Strategy

Accumulation is a term used to describe a market controlled by buyers;
whereas distribution is defined by a market controlled by sellers.
Williams recommends trading this indicator based on divergences:

Distribution of the security is indicated when the security is making
a new high and the A/D indicator is failing to make a new high. Sell.

Accumulation of the security is indicated when the security is making
a new low and the A/D indicator is failing to make a new low. Buy.

WARNING:
- This script to change bars colors.