pep8 and doc

theano/misc/strutil.py

-def renderString(string, dict):
+import warnings
+
+def render_string(string, sub):
+    """
+    string: a string, containing formatting instructions
+    sub: a dictionary containing keys and values to substitute for
+        them.
+
+    returns: string % sub
+
+    The only difference between this function and the % operator
+    is that it raises an exception with a more informative error
+    message than the % operator does.
+    """
     try:
-        finalCode = string % dict
+        finalCode = string % sub
     except Exception , E:
-        #print 'could not render C code due to exception with message "'+str(E)+'", trying to find out why...'
+        # If unable to render the string, render longer and longer
+        # initial substrings until we find the minimal initial substring
+        # that causes an error
         i = 0
         while i <= len(string):
             try:
-                finalCode = string[0:i] % dict
+                finalCode = string[0:i] % sub
             except Exception, F:
                 if str(F) == str(E):
                     raise Exception(string[0:i]+"<<<< caused exception "+str(F))
             i+=1
         assert False
     return finalCode
-#
+
+def renderString(string, dict):
+    warnings.warn("renderString is deprecated. It is now called render_string",
+            stack_level = 2)
+    return render_string(string, dict)
 
 def pretty_format(string):
     lines = string.split('\n')
@@ -34,11 +53,8 @@ def pretty_format(string):
     rval = '\n'.join(lines)
 
     return rval
-#
 
 def strip_leading_white_space(line):
     while len(line) >0 and (line[0]==' ' or line[0]=='\t'):
         line = line[1:]
-    #
     return line
-#