Add support for oauth2client >= 3.0.0, < 4.0.0. (#265)
diff --git a/googleapiclient/channel.py b/googleapiclient/channel.py
index 702186b..7d0feb9 100644
--- a/googleapiclient/channel.py
+++ b/googleapiclient/channel.py
@@ -64,6 +64,13 @@
from oauth2client import util
import six
+# Oauth2client < 3 has the positional helper in 'util', >= 3 has it
+# in '_helpers'.
+try:
+ from oauth2client import util
+except ImportError:
+ from oauth2client import _helpers as util
+
# The unix time epoch starts at midnight 1970.
EPOCH = datetime.datetime.utcfromtimestamp(0)