const type can any type added
for example:
const variable = 1 #init
variable += 1 # error
const type can any type added
for example:
const variable = 1 #init
variable += 1 # error
You should probably look into using typing.Final + a type checker.
To make a change to the language (e.g. runtime Final variables), you would need to put together a much more complete proposal for the semantics of your suggested change. But, bluntly, I don’t think that such a proposal would be likely to succeed and therefore advise against investing that effort in this one.