Rename balance to flow.

accountant/models/accounts.py

@@ -67,8 +67,11 @@ class Account(db.Model):
         ).one()
 
     def balance(self, begin, end):
-        """Return the balance for a specific time period."""
-        # TODO Alexis Lahouze 2017-05-04 Rename to "flow" or "cash flow"
+        """Return the flow for a specific time period."""
+        return self.flow(begin, end)
+
+    def flow(self, begin, end):
+        """Return the flow for a specific time period."""
         query = db.session.query(
             db.func.sum(
                 db.case(