Unicode problems with Python 2.7.

I read the matplotlib rcParams from a json file. The json module
always uses Unicode, but this does not work in Python 2.7. This
was causing the plots not to appear if using Python 2.7.

Wrote code to detect Python version and to convert to ASCII if
Python version 2.

code/book_format.py

@@ -39,6 +39,36 @@ def reset_axis():
     pylab.rcParams['figure.figsize'] = 12, 6
 
 
-s = json.load( open("../code/538.json") )
+def _decode_list(data):
+    rv = []
+    for item in data:
+        if isinstance(item, unicode):
+            item = item.encode('utf-8')
+        elif isinstance(item, list):
+            item = _decode_list(item)
+        elif isinstance(item, dict):
+            item = _decode_dict(item)
+        rv.append(item)
+    return rv
+
+def _decode_dict(data):
+    rv = {}
+    for key, value in data.iteritems():
+        if isinstance(key, unicode):
+            key = key.encode('utf-8')
+        if isinstance(value, unicode):
+            value = value.encode('utf-8')
+        elif isinstance(value, list):
+            value = _decode_list(value)
+        elif isinstance(value, dict):
+            value = _decode_dict(value)
+        rv[key] = value
+    return rv
+
+import sys
+if sys.version_info[0] >= 3:
+    s = json.load( open("../code/538.json"))
+else:
+    s = json.load( open("../code/538.json"), object_hook=_decode_dict)
 plt.rcParams.update(s)
 reset_axis ()