Function add

src/compute-engine/library/statistics.ts:690–691

(ce: ComputeEngine, xs: Expression[])

    PopulationStandardDeviation: {
      complexity: 1200,
      broadcastable: false,
      description: 'Population Standard Deviation of a collection of numbers.',
      signature: '((collection<any>|number)+) -> number',
      // The handler itself stays: deleting it would activate the
      // no-handler fallback, which derives a NARROWER type than this