@type t() :: %ExBifrost.Model.BifrostLlmUsage{
  completion_tokens: integer() | nil,
  completion_tokens_details:
    ExBifrost.Model.ChatCompletionTokensDetails.t() | nil,
  cost: ExBifrost.Model.BifrostCost.t() | nil,
  prompt_tokens: integer() | nil,
  prompt_tokens_details: ExBifrost.Model.ChatPromptTokensDetails.t() | nil,
  total_tokens: integer() | nil
}