diff --git a/relational/maintenance.py b/relational/maintenance.py
index dc6ed20..f55fae4 100644
--- a/relational/maintenance.py
+++ b/relational/maintenance.py
@@ -29,7 +29,7 @@ def send_survey(data):
     post=''
     for i in data.keys():
         post+='%s: %s\n' %(i,data[i])
-    
+
     #sends the string
     params = urllib.urlencode({'survey':post})
     headers = {"Content-type": "application/x-www-form-urlencoded","Accept": "text/plain"}
@@ -48,6 +48,8 @@ def check_latest_version():
     
     #html
     s=r.read()
+    if len(s)==0:
+        return None
     
     l= s[s.find('<ul>')+4:s.find('</ul>')].split('\n')
     l.sort()
diff --git a/relational/optimizer.py b/relational/optimizer.py
index c96ff17..7d5a7bf 100644
--- a/relational/optimizer.py
+++ b/relational/optimizer.py
@@ -50,8 +50,7 @@ def optimize_all(expression,rels,specific=True,general=True,debug=None):
     general: True if it has to perform general optimizations
     debug: if a list is provided here, after the end of the function, it
         will contain the query repeated many times to show the performed
-        steps. Of course don't call optimize_all(... ,debug=[]) because it
-        would make no sense
+        steps.
     
     Return value: this will return an optimized version of the expression'''
     if isinstance(expression,str):
diff --git a/relational/parser.py b/relational/parser.py
index 97f4735..854e0ea 100644
--- a/relational/parser.py
+++ b/relational/parser.py
@@ -85,7 +85,7 @@ class node (object):
         '''Expression from right to left, searching for binary operators
         this means that binary operators have lesser priority than
         unary operators.
-        It find the operator with lesser priority, uses it as root of this
+        It finds the operator with lesser priority, uses it as root of this
         (sub)tree using everything on its left as left parameter (so building
         a left subtree with the part of the list located on left) and doing 
         the same on right.
diff --git a/relational/relation.py b/relational/relation.py
index 11b075a..ed7a870 100644
--- a/relational/relation.py
+++ b/relational/relation.py
@@ -129,7 +129,7 @@ class relation (object):
     def product (self,other):
         '''Cartesian product, attributes must be different to avoid collisions
         Doing this operation on relations with colliding attributes will 
-        cause the return of a None value.
+        cause an exception.
         It is possible to use rename on attributes and then use the product'''
         
         if (self.__class__!=other.__class__)or(self.header.sharedAttributes(other.header)!=0):