How can I copy a section of an image using the gm node package?

I've installed gm node package and I need to be able to copy a section of an image. I'm not sure if its possible to do it using this package.

In PHP it looks like the function I would be looking for is imagecopy

This is about as close as I've got so far:

var im = gm.subClass({imageMagick: true});
im(source)
.crop(coords.w, coords.h)
.write(projectRootServer + 'forrestregion.png', function(err){
   if (err) return console.dir(arguments)
   console.log(this.outname + ' created :: ' + arguments[3])
})

I thought the .region function might do the job but it doesn't look like it.

Can anyone suggest a solution to this?