Cor does not has a keyword to declare variables, instead, Cor declares it for you the first time it is used. If a variable with equal name is declared in outer scope the compiler will assume you are using the declared outside. Unless you write the variable as a simple statement. This technique is called variable announcing.
Sadly, it's the same mistake that CoffeeScript made: you cannot just introduce a variable, to be completely sure you didn't break anything, you'll have to search for all uses of it in outer scope above and inner scopes below.