I'm not sure I understand this, but I think you're still thinking in Scratch terms, in which lists are sort of parallel to variables. They both have names and values, but a variable has one value and a list has a bunch of values.
But that's not how it works in 
. A list is a value. One value, no matter how many items are in the list. The value 47 doesn't have a name, and neither does the value (781 47 99).
Variables have names. Their job is to associate a name with a value. (Fine print: The real truth is that the job of a variable is to associate a name with a location in memory. You can put any (one) value you like (including a list) into that location in memory, using SET. I knew that that was the official story, but never understood why until we invented upvars. You don't have to worry about it.)
So "the variable has been turned into a list" doesn't mean anything. It's like, I don't know, "the pumpkin has been turned into happily"; it doesn't mean anything because "happily" doesn't fit into that slot in a sentence.
You can assign a list value to a variable, same as any other value. But you can't just declare that 42 is a list. Like it or not, 42 is a number.