@Override
        public double getAmount(@Nonnull Random random) {
            if (random.nextDouble() < this.chance) {
                return this.inner.getAmount(random);
            }
            return this.base;
        }
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