Creating custom struct/map and adding to list issue

when i print that list out here is stays empty, and the console says this when i start to run the app:

warning: variable "teams_with_scores" is unused

Note variables defined inside case, cond, fn, if and similar do not leak. If you want to conditionally override an existing variable "teams_with_scores", you will have to explicitly return the variable. For example:

if some_condition? do
  atom = :one
else
  atom = :two
end

should be written as

atom =
  if some_condition? do
    :one
  else
    :two
  end

So what i understand form this is that this:

is not able to to what I want, but I don’t understand how to make it so, what does the console’s message mean?