@type product() :: %{
  optional(:active) => boolean(),
  optional(:id) => binary(),
  optional(:metadata) => %{optional(binary()) => binary()},
  optional(:name) => binary(),
  optional(:statement_descriptor) => binary(),
  optional(:tax_code) => binary(),
  optional(:unit_label) => binary()
}

The product whose pricing the created plan will represent. This can either be the ID of an existing product, or a dictionary containing fields used to create a service product.

@type t() :: %Stripe.Plan{
  active: boolean(),
  aggregate_usage: binary() | nil,
  amount: integer() | nil,
  amount_decimal: binary() | nil,
  billing_scheme: binary(),
  created: integer(),
  currency: binary(),
  id: binary(),
  interval: binary(),
  interval_count: integer(),
  livemode: boolean(),
  metadata: term() | nil,
  nickname: binary() | nil,
  object: binary(),
  product: (binary() | Stripe.Product.t() | Stripe.DeletedProduct.t()) | nil,
  tiers: term(),
  tiers_mode: binary() | nil,
  transform_usage: term() | nil,
  trial_period_days: integer() | nil,
  usage_type: binary()
}

The plan type.

• active Whether the plan can be used for new purchases.
• aggregate_usage Specifies a usage aggregation strategy for plans of usage_type=metered. Allowed values are sum for summing up all usage during a period, last_during_period for using the last usage record reported within a period, last_ever for using the last usage record ever (across period bounds) or max which uses the usage record with the maximum reported usage during a period. Defaults to sum.
• amount The unit amount in cents (or local equivalent) to be charged, represented as a whole integer if possible. Only set if billing_scheme=per_unit.
• amount_decimal The unit amount in cents (or local equivalent) to be charged, represented as a decimal string with at most 12 decimal places. Only set if billing_scheme=per_unit.
• billing_scheme Describes how to compute the price per period. Either per_unit or tiered. per_unit indicates that the fixed amount (specified in amount) will be charged per unit in quantity (for plans with usage_type=licensed), or per unit of total usage (for plans with usage_type=metered). tiered indicates that the unit pricing will be computed using a tiering strategy as defined using the tiers and tiers_mode attributes.
• created Time at which the object was created. Measured in seconds since the Unix epoch.
• currency Three-letter ISO currency code, in lowercase. Must be a supported currency.
• id Unique identifier for the object.
• interval The frequency at which a subscription is billed. One of day, week, month or year.
• interval_count The number of intervals (specified in the interval attribute) between subscription billings. For example, interval=month and interval_count=3 bills every 3 months.
• livemode Has the value true if the object exists in live mode or the value false if the object exists in test mode.
• metadata Set of key-value pairs that you can attach to an object. This can be useful for storing additional information about the object in a structured format.
• nickname A brief description of the plan, hidden from customers.
• object String representing the object's type. Objects of the same type share the same value.
• product The product whose pricing this plan determines.
• tiers Each element represents a pricing tier. This parameter requires billing_scheme to be set to tiered. See also the documentation for billing_scheme.
• tiers_mode Defines if the tiering price should be graduated or volume based. In volume-based tiering, the maximum quantity within a period determines the per unit price. In graduated tiering, pricing can change as the quantity grows.
• transform_usage Apply a transformation to the reported usage or set quantity before computing the amount billed. Cannot be combined with tiers.
• trial_period_days Default number of trial days when subscribing a customer to this plan using trial_from_plan=true.
• usage_type Configures how the quantity per period should be determined. Can be either metered or licensed. licensed automatically bills the quantity set when adding it to a subscription. metered aggregates the total usage based on usage records. Defaults to licensed.

@type transform_usage() :: %{
  optional(:divide_by) => integer(),
  optional(:round) => :down | :up
}

Apply a transformation to the reported usage or set quantity before computing the billed price. Cannot be combined with tiers.