# `LatticeStripe.Billing.Meter.DefaultAggregation`
[🔗](https://github.com/szTheory/lattice_stripe/blob/v2.2.2/lib/lattice_stripe/billing/meter/default_aggregation.ex#L1)

Aggregation formula for a `LatticeStripe.Billing.Meter`.

One of three Stripe-documented formulas:
- `"sum"` — sum of `value_settings.event_payload_key` across events
- `"count"` — number of events (value_settings ignored)
- `"last"` — most recent `value_settings.event_payload_key` in window

# `formula`

```elixir
@type formula() :: String.t()
```

# `t`

```elixir
@type t() :: %LatticeStripe.Billing.Meter.DefaultAggregation{formula: formula() | nil}
```

# `from_map`

```elixir
@spec from_map(map() | nil) :: t() | nil
```

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*Consult [api-reference.md](api-reference.md) for complete listing*