code: func Convolve3x3(img image.Image, kernel [9]float64, options *ConvolveOptions) *image.NRGBA {
  	return convolve(img, kernel[:], options)
  }
docs: // Convolve3x3 convolves the image with the specified 3x3 convolution kernel.
  // Default parameters are used if a nil *ConvolveOptions is passed.