diff --git a/quantdsl/semantics.py b/quantdsl/semantics.py
index 7e0e3fd..87c9d66 100644
--- a/quantdsl/semantics.py
+++ b/quantdsl/semantics.py
@@ -152,11 +152,11 @@ def assert_args_arg(self, args, posn, required_type):
             desc += str(args[posn])
             raise DslSyntaxError(error_msg, desc, self.node)
 
-    def list_instances(self, dsl_type):
-        return list(self.find_instances(dsl_type))
+    def list_instances(self, *dsl_types):
+        return list(self.find_instances(*dsl_types))
 
-    def has_instances(self, dsl_type):
-        for _ in self.find_instances(dsl_type):
+    def has_instances(self, *dsl_types):
+        for _ in self.find_instances(*dsl_types):
             return True
         else:
             return False
@@ -729,13 +729,13 @@ def apply(self, dsl_globals=None, present_time=None, observation_date=None, pend
         call_cache_key_dict = {}
         for arg_name, arg_value in raw_dsl_locals.items():
             if isinstance(arg_value, FunctionCall):
-                if not list(arg_value.functionDef.find_instances(FunctionCall, StochasticObject)):
+                if not arg_value.functionDef.list_instances(FunctionCall, StochasticObject):
                     try:
                         arg_value = arg_value.call_functions()
                     except DslError as e:
                         raise Exception("Can't evaluate {}: {}: {}".format(arg_name, arg_value, e))
             elif isinstance(arg_value, DslExpression):
-                if not arg_value.find_instances(StochasticObject):
+                if not arg_value.list_instances(StochasticObject):
                     try:
                         arg_value = arg_value.evaluate()
                     except DslError as e:
@@ -824,8 +824,8 @@ def create_hash(self, obj):
         if isinstance(obj, dict):
             return hash(tuple(sorted([(a, self.create_hash(b)) for a, b in obj.items()])))
 
-        if isinstance(obj, list):
-            return hash(tuple(sorted([self.create_hash(a) for a in obj])))
+        # if isinstance(obj, list):
+        #     return hash(tuple(sorted([self.create_hash(a) for a in obj])))
 
         raise DslSystemError("Can't create hash from obj type '%s'" % type(obj), obj,
                              node=obj.node if isinstance(obj, DslObject) else None)
diff --git a/quantdsl/tests/test_application.py b/quantdsl/tests/test_application.py
index 3c8abe4..a47b66a 100644
--- a/quantdsl/tests/test_application.py
+++ b/quantdsl/tests/test_application.py
@@ -1219,22 +1219,22 @@ def ProfitFromRunning(start_date, underlying, time_since_off):
         # Check single-sided vs. double sided deltas.
         self.assert_contract_value(specification.format(end_date='2012-01-13'),
                                    expected_value=11.771,
-                                   expected_call_count=47,
+                                   expected_call_count=37,
                                    periodisation='monthly',
                                    expected_deltas={'SPARKSPREAD-2012-1': 11.978})
 
         self.assert_contract_value(specification.format(end_date='2012-01-13'),
                                    expected_value=11.771,
-                                   expected_call_count=47,
+                                   expected_call_count=37,
                                    periodisation='monthly',
                                    expected_deltas={'SPARKSPREAD-2012-1': 11.978},
                                    is_double_sided_deltas=False)
 
         # Check the call counts.
-        self.assert_contract_value(specification.format(end_date='2012-01-13'), 11.771, expected_call_count=47)
-        self.assert_contract_value(specification.format(end_date='2012-01-14'), expected_call_count=51)
-        self.assert_contract_value(specification.format(end_date='2012-01-15'), expected_call_count=55)
-        self.assert_contract_value(specification.format(end_date='2012-01-16'), expected_call_count=59)
+        self.assert_contract_value(specification.format(end_date='2012-01-13'), 11.771, expected_call_count=37)
+        self.assert_contract_value(specification.format(end_date='2012-01-14'), expected_call_count=40)
+        self.assert_contract_value(specification.format(end_date='2012-01-15'), expected_call_count=43)
+        self.assert_contract_value(specification.format(end_date='2012-01-16'), expected_call_count=46)
 
     def test_generate_valuation_power_plant_option_power_and_gas_forward(self):
         specification = """
@@ -1290,11 +1290,11 @@ def Tomorrow(today):
 
 PowerPlant(Date('2012-1-1'), Date('{end_date}'), Stopped(2))
         """
-        self.assert_contract_value(specification.format(end_date='2012-01-13'), 22.195, expected_call_count=47)
-        self.assert_contract_value(specification.format(end_date='2012-01-14'), expected_call_count=51)
-        self.assert_contract_value(specification.format(end_date='2012-01-15'), expected_call_count=55)
-        self.assert_contract_value(specification.format(end_date='2012-01-16'), expected_call_count=59)
-        self.assert_contract_value(specification.format(end_date='2012-01-17'), expected_call_count=63)
+        self.assert_contract_value(specification.format(end_date='2012-01-13'), 22.195, expected_call_count=37)
+        self.assert_contract_value(specification.format(end_date='2012-01-14'), expected_call_count=40)
+        self.assert_contract_value(specification.format(end_date='2012-01-15'), expected_call_count=43)
+        self.assert_contract_value(specification.format(end_date='2012-01-16'), expected_call_count=46)
+        self.assert_contract_value(specification.format(end_date='2012-01-17'), expected_call_count=49)
 
     def test_call_recombinations_with_function_calls_advancing_values(self):
         # This wasn't working, because each function call was being carried into the next
@@ -1319,7 +1319,7 @@ def f2(d):
 
 f(9, 1)
 """
-        self.assert_contract_value(specification, expected_call_count=28)
+        self.assert_contract_value(specification, expected_call_count=20)
 
 
 class TestObservationDate(ApplicationTestCase):