Calculate statistics iteratively
When the number of samples is less then required, methods from this crate usually returns `NaN`. It's correct, but requires user to check the result or verify the number of samples. Maybe return `Option` instead? This will be consistent with other methods on `Iterator`.
This issue appears to be discussing a feature request or bug report related to the repository. Based on the content, it seems to be still under discussion. The issue was opened by Shatur and has received 2 comments.