let api = CryptoCompareAPI(applicationName: "MyApp")
    
// Retrieve all coins (actually this is not the whole coin list
// from cryptocompare API, but this endpoint is useful anyway
api.send(GetCoinListRequest()) {
  switch $0 {
  case .success(let coinList):
    // Process coinList here

  case .failure(let error):
    // Handle error state
    print(error.description)
  }
}

let request = GetSymbolsPriceRequest(fsyms: "BTC,ETH",
                                     tsyms: "USD",
                                     e: .binance)
    
api.send(request) {
  switch $0 {
  case .success(let prices):
    // Process prices here

  case .failure(let error):
    // Handle error state
    print(error.description)
  }
}

import Promises
import CryptoCompareAPI

extension CryptoCompareAPI {
  func send<T: APIRequest>(_ request: T) -> Promise<T.Response> {
    return Promise { fulfill, reject in
      self.send(request) {
        switch $0 {
        case .success(let value):
          fulfill(value)
          
        case .failure(let error):
          reject(error)
        }
      }
    }
  }
}

let dataTask = api.send(request)
...
if userWantsToCancelUpdate {
  dataTask.cancel()
}