Function flattenArguments

src/compute-engine/library/statistics.ts:648–656

(
  args: ReadonlyArray<Expression>
)

      complexity: 1200,
      broadcastable: false,
      signature: '((collection<any>|number|distribution)+) -> number',
      // A data-consuming aggregate (§3.C): result type is the numeric base
      // with NO `| missing` arm (I6 absorption) — `number`, NOT `real`,
      // because every arm of the wide type is reachable. An absent datum or
      // empty input evaluates to `NaN` (`Mean([1, NaN, 3])`, `Mean([])`);
      // infinite data keeps its limit (`Mean([1, +oo, 3])` is `+oo`); and
      // complex data has a complex mean (`Mean([1, 1+2i])` is `1 + i`).
      // Three named arms would be needed to say less, so the base type says
      // it in one token.
      //
      // The operand carrier stays `collection<any>` — the ABSENCE-admitting
      // top — because the §3.C rule requires `[1, Missing, 3]` to REACH this