@Override
        public String toString() {
            return "VariableAmount.OptionalAmount(base=" + this.base + ", chance=" + this.chance + ", inner=" + this.inner + ")";
        }
Represents a variable amount which has a base and a chance of varying.
This wraps another {@link VariableAmount} which it refers to if the
chance succeeds.
helper/src/main/java/me/lucko/helper/random/VariableAmount.java