CHALLENGE 3: Union Type for Status
===================================

SOLUTION:

type Status = "pending" | "approved" | "rejected";

function handleStatus(status: Status): void {
  if (status === "pending") {
    console.log("The request is waiting for review...");
  } else if (status === "approved") {
    console.log("The request has been approved!");
  } else if (status === "rejected") {
    console.log("The request was rejected.");
  }
}

// Using the function:
handleStatus("approved");  // ✅ Works
handleStatus("pending");   // ✅ Works
handleStatus("rejected");  // ✅ Works
handleStatus("ignored");   // ❌ Error! "ignored" is not a valid Status

EXPLANATION:
- "type Status = ..." — defines a union type
- "pending" | "approved" | "rejected" — only these exact strings are valid
- handleStatus(status: Status) — function only accepts a Status value
- TypeScript catches typos: handleStatus("aproved") would error immediately

WHY UNION TYPES MATTER:
- Type safety for a fixed set of options
- IDE autocomplete shows only valid options
- Prevents bugs from typos: "aproved" instead of "approved"
- Self-documenting: the type itself explains valid options

ALTERNATIVE SOLUTION (with switch):

function handleStatus(status: Status): void {
  switch (status) {
    case "pending":
      console.log("Waiting for review...");
      break;
    case "approved":
      console.log("Approved!");
      break;
    case "rejected":
      console.log("Rejected.");
      break;
  }
}

OR WITH OBJECT MAPPING:

const statusMessages: Record<Status, string> = {
  pending: "The request is waiting for review...",
  approved: "The request has been approved!",
  rejected: "The request was rejected."
};

function handleStatus(status: Status): void {
  console.log(statusMessages[status]);
}

TESTING:
handleStatus("pending")    // ✅ Logs message
handleStatus("approved")   // ✅ Logs message
handleStatus("rejected")   // ✅ Logs message
handleStatus("unknown")    // ❌ Error! Not a valid Status
handleStatus("Approved")   // ❌ Error! Capital A—must match exactly

KEY INSIGHT:
Union types with string literals create an enum-like type without the overhead.
Very common pattern in real TypeScript codebases.