Apply suggestions from code review

Author: johnzhou721

Lib/idlelib/editor.py

@@ -1202,9 +1202,7 @@ def load_extension(self, name):
         if keydefs:
             self.apply_bindings(keydefs)
             for vevent in keydefs:
-                methodname = vevent.replace("-", "_")
-                methodname = methodname.lstrip('<').rstrip('>')
-                methodname = methodname + "_event"
+                methodname = vevent.lstrip("<").replace("-", "_").rstrip(">") + "_event"
                 if hasattr(ins, methodname):
                     self.text.bind(vevent, getattr(ins, methodname))