pub unsafe extern "system" fn clCreateContextFromType( properties: *const cl_context_properties, device_type: cl_device_type, pfn_notify: Option<extern "C" fn(_: *const c_char, _: *const c_void, _: size_t, _: *mut c_void)>, user_data: *mut c_void, errcode_ret: *mut cl_int) -> cl_context