How to override native function with Puppeteer

Normally I would do it with

await page.evaluateOnNewDocument(my_js_code);

where my_js_code is something like:

Object.defineProperty(HTMLCanvasElement.prototype, "toBlob", ...

But the problem is that after that the code becomes visible

console.log(HTMLCanvasElement.prototype.toBlob.toString());

With the native function the code is not visible, toString returns [native code], not the actual code

So, is there a way I can override a function at a deeper level with Pupeteer?

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