Function sample 

pub fn sample(policy: &[f64], rng: &mut StdRng) -> usize

Samples an action index from a given policy distribution using a random number generator.

This function performs a weighted random selection, where actions with higher policy probabilities are more likely to be chosen.

Parameters

• policy: A slice representing the probability distribution over actions. The sum of probabilities should ideally be 1.0.
• rng: A mutable reference to a StdRng (standard random number generator) instance. This allows for reproducible sampling if the RNG is seeded.

Returns

The index of the sampled action.

Panics

Panics if the policy slice is empty and if no action is selected (should not happen if policy sums to 1.0).