edit accounts.py
-    @property
-    def balance(self):
-        """Current USD balance as a float."""
-        return self._balance
-    def deposit(self, amount):
=======
+    @property
+    def balance(self):
+        """Current USD balance as a float."""
+        return self._balance
+
+    def currencies(self):
+        """Return a sorted list of currency codes held by this account."""
+        return ["USD"]
+
+    def deposit(self, amount):
>>>>>>>
