pub type PFN_vkGetPhysicalDeviceOpticalFlowImageFormatsNV = unsafe extern "system" fn(_physical_device: PhysicalDevice, _optical_flow_image_format_info: *const OpticalFlowImageFormatInfoNV, _format_count: *mut u32, _image_format_properties: *mut OpticalFlowImageFormatPropertiesNV) -> Result;