Version 22: Update with mask

Now the update function includes an extra boolean parameter, mask. When true, the update will apply as a mask. So if your document looks like this:

{ number: 1, text: "Hello" }

and you call update with mask = true with this object as your mask:

{ number: 2 } 

then the number field will be updated, but the text field will not. The resulting document will be

{ number: 2, text: "Hello" }

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Thanks to @webstermath for this feature!