24171: Py3 fixes

Author: rwst

src/sage/sets/real_set.py

@@ -796,6 +796,8 @@ def get_interval(self, i):
         """
         return self._intervals[i]
 
+    __getitem__ = get_interval
+
     def object(self):
         """
         Return the underlying object of ``self``.
@@ -807,7 +809,7 @@ def object(self):
         """
         return self
 
-    def __nonzero__(self):
+    def __bool__(self):
         """
         A set is considered True unless it is empty, in which case it is
         considered to be False.
@@ -821,7 +823,7 @@ def __nonzero__(self):
         """
         return not self.is_empty()
 
-    __getitem__ = get_interval
+    __nonzero__ = __bool__
 
     @staticmethod
     def normalize(intervals):