Update Lab 08 assignment: one more method in interface

08-lambdas-and-stream-api/lab/README.md

@@ -67,10 +67,18 @@ public interface TransactionAnalyzer {
      */
     List<Transaction> allTransactionsByUser(String accountId);
 
+    /**
+     * Returns the risk rating of an account with the specified ID.
+     *
+     * @return the risk rating as a double-precision floating-point number in the interval [0.0, 1.0].
+     * @throws IllegalArgumentException if the account ID is null or empty.
+     */
+    double accountRating(String accountId);
+
     /**
      * Calculates the risk score for each account based on the loaded rules.
-     * The score for each account is a double-precision floating-point number in the interval [0, 1]
-     * and is formed by summing up the weights of all applicable rules to the account transactions.
+     * The score for each account is a double-precision floating-point number in the interval [0, 1] and is formed
+     * by summing up the weights of all applicable rules to the account transactions.
      * The result is sorted in descending order, with the highest-risk accounts listed first.
      *
      * @return a map where keys are account IDs (strings) and values are risk scores (doubles).