diff --git a/rdflib/graph.py b/rdflib/graph.py
index 19ce254ac..905f6d0ea 100644
--- a/rdflib/graph.py
+++ b/rdflib/graph.py
@@ -1,9 +1,7 @@
 from rdflib.term import Literal  # required for doctests
-l = Literal('')
-del l
+assert Literal # avoid warning
 from rdflib.namespace import Namespace  # required for doctests
-n = Namespace('xxx')
-del n
+assert Namespace # avoid warning
 from rdflib.py3compat import format_doctest_out
 
 __doc__ = format_doctest_out("""\
diff --git a/rdflib/term.py b/rdflib/term.py
index 25c22c5cb..546482a6e 100644
--- a/rdflib/term.py
+++ b/rdflib/term.py
@@ -148,7 +148,7 @@ def __gt__(self, other):
         This tries to implement this:
         http://www.w3.org/TR/sparql11-query/#modOrderBy
 
-        Variables are no included in the SPARQL list, but
+        Variables are not included in the SPARQL list, but
         they are greater than BNodes and smaller than everything else
 
         """
@@ -190,10 +190,6 @@ def __hash__(self):
 class URIRef(Identifier):
     """
     RDF URI Reference: http://www.w3.org/TR/rdf-concepts/#section-Graph-URIref
-
-    The URIRef constructor will do a limited check for valid URIs,
-    essentially just making sure that the string includes no illegal
-    characters (``<, >, ", {, }, |, \\, `, ^``)
     """
 
     __slots__ = ()
@@ -220,6 +216,15 @@ def toPython(self):
         return unicode(self)
 
     def n3(self, namespace_manager = None):
+        """
+        This will do a limited check for valid URIs,
+        essentially just making sure that the string includes no illegal
+        characters (``<, >, ", {, }, |, \\, `, ^``)
+
+        :param namespace_manager: if not None, will be used to make up
+             a prefixed name
+        """
+
         if not _is_valid_uri(self):
             raise Exception('"%s" does not look like a valid URI, I cannot serialize this as N3/Turtle. Perhaps you wanted to urlencode it?'%self)