It's an extension function to convert retrofit Call to a coroutine

Retrofit Call coroutine extention

    suspend fun <T> Call<T>.await(): T = suspendCoroutine { continuation ->

        enqueue(object : Callback<T> {
            override fun onFailure(call: Call<T>, t: Throwable) {
                continuation.resumeWithException(t)
            }

            override fun onResponse(call: Call<T>, response: Response<T>) {
                if (response.isSuccessful)
                    continuation.resume(response.body()!!)
                else
                    continuation.resumeWithException(HttpException(response)) // You can map the exception to anything you need
            }
        })
    }