@type t() :: %Paypal.Subscription.Plan.BillingCycle{
  frequency: map() | nil,
  pricing_scheme: map() | nil,
  sequence: integer() | nil,
  tenure_type: any() | nil,
  total_cycles: integer() | nil
}

Billing cycle definition:

• tenure_type - Cycle type: :regular or :trial.
• sequence - The order of the cycle (1, 2, etc.).
• total_cycles - Number of times cycle repeats (0 for infinite).
• frequency - Map with interval_unit ("DAY", "WEEK", "MONTH", "YEAR") and interval_count.
• pricing_scheme - Map with fixed_price (containing currency_code and value).