t() :: %ExFtx.Position{
  collateral_used: number(),
  cost: number(),
  entry_price: number(),
  estimated_liquidation_price: number(),
  future: String.t(),
  initial_margin_requirement: number(),
  long_order_size: number(),
  maintenance_margin_requirement: number(),
  net_size: number(),
  open_size: number(),
  realized_pnl: number(),
  short_order_size: number(),
  side: String.t(),
  size: number(),
  unrealized_pnl: number()
}