Function pooled_totals 

pub fn pooled_totals(rows: &[(u64, u64)]) -> Result<Totals, SerpError>

Pool (clicks, impressions) rows into a single Totals.

Pooling is not the same as averaging the CTR column, and the difference is the classic Simpson’s-paradox trap in SEO reporting.

Errors

SerpError::EmptyInput for an empty slice, SerpError::NoImpressions when the totals contain no impressions.