   
   /**
    Create `stillImageoutput` and add it to `captureSession`.
-   - Throws: `CaptureManagerError.InvalidCaptureOutput` if the output cannot be added to `captureSession`.
+   - Throws: `CaptureManagerError.invalidCaptureOutput` if the output cannot be added to `captureSession`.
    */
   fileprivate func addStillImageOutput() throws {
     stillImageOutput = AVCaptureStillImageOutput()

   
   - parameter type: The media type, such as AVMediaTypeVideo, AVMediaTypeAudio, or AVMediaTypeMuxed.
   - parameter position: The `AVCaptureDevicePosition`. If nil, `videoDevicePosition` is used.
   - Throws: `CaptureManagerError.InvalidMediaType` if `type` is not a valid media type.
   - Returns: `AVCaptureDevice?`
   */
  fileprivate func desiredDevice(withMediaType type: String, position: AVCaptureDevicePosition? = nil) throws -> AVCaptureDevice {

  
  /**
   Set the sessionPreset for the AVCaptureSession.
   - Throws: `CaptureManager.invalidSessionPresent` if `sessionPreset` is not valid.
   */
  fileprivate func setSessionPreset(_ preset: String) throws {
    if !captureSession.canSetSessionPreset(preset) {
