Replace backticks with repr() or "%r"

From SF patch #852334.
diff --git a/Demo/metaclasses/Enum.py b/Demo/metaclasses/Enum.py
index 13a3ed7..df1d814 100644
--- a/Demo/metaclasses/Enum.py
+++ b/Demo/metaclasses/Enum.py
@@ -107,9 +107,9 @@
         return self.__value
 
     def __repr__(self):
-        return "EnumInstance(%s, %s, %s)" % (`self.__classname`,
-                                             `self.__enumname`,
-                                             `self.__value`)
+        return "EnumInstance(%r, %r, %r)" % (self.__classname,
+                                             self.__enumname,
+                                             self.__value)
 
     def __str__(self):
         return "%s.%s" % (self.__classname, self.__enumname)
diff --git a/Demo/metaclasses/Meta.py b/Demo/metaclasses/Meta.py
index 39cbef6..5534074 100644
--- a/Demo/metaclasses/Meta.py
+++ b/Demo/metaclasses/Meta.py
@@ -98,7 +98,7 @@
         def __init__(self, *args):
             print "__init__, args =", args
         def m1(self, x):
-            print "m1(x=%s)" %`x`
+            print "m1(x=%r)" % (x,)
     print C
     x = C()
     print x
diff --git a/Demo/metaclasses/Trace.py b/Demo/metaclasses/Trace.py
index 86e199d..ea12cd9 100644
--- a/Demo/metaclasses/Trace.py
+++ b/Demo/metaclasses/Trace.py
@@ -117,7 +117,7 @@
         def m2(self, y): return self.x + y
         __trace_output__ = sys.stdout
     class D(C):
-        def m2(self, y): print "D.m2(%s)" % `y`; return C.m2(self, y)
+        def m2(self, y): print "D.m2(%r)" % (y,); return C.m2(self, y)
         __trace_output__ = None
     x = C(4321)
     print x