This exact thing came up on the list before I'm sure.
A case of where we need some sort of repository of this sort of knowledge. Mailing lists archives are not exactly the right platform for storage abd search of code idioms and samples.
Just musing. Andrew Vaughan McAlley wrote on 25/01/2021 3:17 PM:
I am trying to write a function that will accept a symbol and a value, and assign that value to the symbol /if the variable has not already been defined /(such as in an include file).
