(fix): concrete signature return types

src/exercises/concrete/concurrencyAbort/README.md

@@ -10,6 +10,6 @@ A concrete example where we employ this strategy is to **deduplicate** calls tha
 
 Implement a function that:
 
-- Signature: `(input: string) => Promise<string>`
+- Signature: `(input: string) => Promise<void>`
 - Calls `fetchData` (async) with the `input` and calls `setData` (sync) with the result
 - Whenever the function is called while it is already running, the latest call should be aborted

src/exercises/concrete/concurrencyEnqueue/README.md

@@ -10,6 +10,6 @@ A concrete example where we employ this strategy is when showing toasts, where w
 
 Implement a function that:
 
-- Signature: `(input: string) => Promise<string>`
+- Signature: `(input: string) => Promise<void>`
 - Calls `postData` (async) with the `input`, once all previous calls resolved
 - Whenever the function is called while it is already running, subsequent calls should be enqueued and run in order

src/exercises/concrete/concurrencyOverride/README.md

@@ -18,7 +18,7 @@ In this exercise, we're going to implement a function that calls an async functi
 
 Implement a function that:
 
-- Signature: `(input: string) => Promise<string>`
+- Signature: `(input: string) => Promise<void>`
 - Calls `fetchFirstData` (async) with the `input`
 - Calls `fetchSecondData` (async) with `fetchFirstData` result
 - Calls `setData` (sync) with `fetchSecondData` result

src/exercises/concrete/parallelCollectErrors/README.md

@@ -12,6 +12,6 @@ In this exercise, we'll make calls to `postData` in parallel and collect the err
 
 Implement a function that:
 
-- Signature: `(list: Array<string>) => Promise<Array<string>>`
+- Signature: `(list: Array<string>) => Promise<{ successes: Array<string>; errors: Array<unknown> }>`
 - Calls `postData` with each element in `list` in parallel
 - Returns an object with keys `successes` and `errors`, where `successes` is the list of results of `postData` and `errors` is the list of errors thrown by `postData`

src/exercises/concrete/serial/README.md

@@ -14,7 +14,7 @@ In this case, even though there are **no data dependencies** between these tasks
 
 Implement a function that:
 
-- Signature: `(list: Array<string>) => Promise<string>`
+- Signature: `(list: Array<string>) => Promise<Array<string>>`
 - Calls `postData` with each item in `list` in order
 - Each subsequent `postData` call should wait for the previous one to complete
 - Returns a list of the results of each `postData` call in the order they were called

src/exercises/concrete/serialCollectErrors/README.md

@@ -8,6 +8,6 @@ This exercise is very similar to the `concrete/serial` one, however, in this cas
 
 Implement a function that:
 
-- Signature: `(list: Array<string>) => Promise<Array<string>>`
+- Signature: `(list: Array<string>) => Promise<{ successes: Array<string>; errors: Array<unknown> }>`
 - Calls `postData` with each element in `list` in series
 - Returns an object with keys `successes` and `errors`, where `successes` is the list of results of `postData` and `errors` is the list of errors thrown by `postData`