Drop iscoroutinefunction fallback function for unsupported python

vcr/cassette.py

@@ -4,6 +4,7 @@ import copy
 import inspect
 import logging
 import sys
+from asyncio import iscoroutinefunction
 
 import wrapt
 
@@ -16,14 +17,6 @@ from .record_mode import RecordMode
 from .serializers import yamlserializer
 from .util import partition_dict
 
-try:
-    from asyncio import iscoroutinefunction
-except ImportError:
-
-    def iscoroutinefunction(*args, **kwargs):
-        return False
-
-
 log = logging.getLogger(__name__)