Python 3.9 compatibility

bench_class.py

@@ -1,7 +1,7 @@
 from collections import namedtuple
 from dataclasses import dataclass
 import typing
-
+import sys
 
 def attributes_in_class():
     class Pet:
@@ -46,15 +46,16 @@ def attributes_in_dataclass():
         dog = Pet(4, "woof")
         str(dog)
 
-def attributes_in_dataclass_with_slots():
-    @dataclass(slots=True)
-    class Pet:
-        legs: int
-        noise: str
+if sys.version_info.minor >= 10:
+    def attributes_in_dataclass_with_slots():
+        @dataclass(slots=True)
+        class Pet:
+            legs: int
+            noise: str
         
-    for _ in range(100000):
-        dog = Pet(4, "woof")
-        str(dog)
+        for _ in range(100000):
+            dog = Pet(4, "woof")
+            str(dog)
 
 def attributes_in_namedtuple():
     Pet = namedtuple("Pet", "legs noise")
@@ -78,10 +79,12 @@ def attributes_in_dict():
 
 __benchmarks__ = [ 
     (attributes_in_dataclass, attributes_in_class, "Class instead of dataclass"),
-    (attributes_in_dataclass, attributes_in_dataclass_with_slots, "dataclass with slots"),
     (attributes_in_dataclass, attributes_in_namedtuple, "Namedtuple instead of dataclass"),
     (attributes_in_namedtuple, attributes_in_class, "class instead of namedtuple"),
     (attributes_in_namedtuple, attributes_in_namedtuple_type, "namedtuple class instead of namedtuple"),
     (attributes_in_class, attributes_in_dict, "dict instead of class"),
-    (attributes_in_class, attributes_in_class_with_slots, "class with slots"),
+    (attributes_in_class, attributes_in_class_with_slots, "class with slots")
 ]
+if sys.version_info.minor >= 10:
+    __benchmarks__.append((attributes_in_dataclass, attributes_in_dataclass_with_slots, "dataclass with slots"))
+