Hello, I would like to set the default value of some value property based on the result of executing an Opaque Expression (as in the screenshot below):

For example, let's say there is some block with the value properties P1, P2 and P3. P1 and P2 have default values that are manually assigned (e.g. P1=1 and P2=2). I would like the default value of P3 to store the result of the operation P1+P2.

Is there any example/tutorial for such a case?

Thank you.