use items/values for python2/3 compat

skimage/io/_plugins/plugin.py

@@ -12,13 +12,6 @@ except ImportError:
 import os.path
 from glob import glob
 
-# Python2/3 compatibility
-import sys
-PY2 = sys.version_info[0] == 2
-if PY2:
-    itervalues = lambda d: d.itervalues()
-else:
-    itervalues = lambda d: d.values()
 
 plugin_store = None
 
@@ -182,7 +175,7 @@ def available(loaded=False):
 
     """
     active_plugins = set()
-    for plugin_func in itervalues(plugin_store):
+    for plugin_func in plugin_store.values():
         for plugin, func in plugin_func:
             active_plugins.add(plugin)