diff -r 14e78f48ac2b -r 58ec6da75f6f task4/solution04/src/org/apidesign/apifest08/currency/ExchangeRateFinder.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/task4/solution04/src/org/apidesign/apifest08/currency/ExchangeRateFinder.java	Sat Oct 11 23:38:46 2008 +0200
@@ -0,0 +1,22 @@
+package org.apidesign.apifest08.currency;
+
+import java.util.Currency;
+
+
+/**
+ * Used to look up the exchange rate between two currencies.
+ *
+ * @author D'Arcy Smith
+ * @version 1.0
+ */
+public interface ExchangeRateFinder
+{
+    /**
+     * Find the exchange rate between two currencies.
+     *
+     * @param a the currency to convert from.
+     * @param b the currency to convert to.
+     * @return the exchange rate for conversions between the two currencies.
+     */
+    ExchangeRate findRate(Currency a, Currency b);
+}