You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: internal.go
    path of file: ./repos/imageserver/image/internal
    
    the code of the file until where you have to start completion: // Package internal provides utilities functions used in the image package.
package internal

import (
	"image"
	"image/color"
	"image/draw"

	"github.com/pierrre/imageutil"
)

// NewDrawable returns a new draw.Image with the same type and size as p.
//
// If p has no size, 1x1 is used.
//
// See NewDrawableSize.
fun
    
func Copy(dst draw.Image, src image.Image) {
	bd := src.Bounds().Intersect(dst.Bounds())
	at := imageutil.NewAtFunc(src)
	set := imageutil.NewSetFunc(dst)
	imageutil.Parallel1D(bd, func(bd image.Rectangle) {
		for y := bd.Min.Y; y < bd.Max.Y; y++ {
			for x := bd.Min.X; x < bd.Max.X; x++ {
				r, g, b, a := at(x, y)
				set(x, y, r, g, b, a)
			}
		}
	})
}