Doc: Erase some unnecessary quotes

Doc/reference/datamodel.rst

@@ -34,7 +34,7 @@ represented by objects.)
 
 Every object has an identity, a type and a value.  An object's *identity* never
 changes once it has been created; you may think of it as the object's address in
-memory.  The ':keyword:`is`' operator compares the identity of two objects; the
+memory.  The :keyword:`is` operator compares the identity of two objects; the
 :func:`id` function returns an integer representing its identity.
 
 .. impl-detail::
@@ -81,16 +81,16 @@ are still reachable.
 
 Note that the use of the implementation's tracing or debugging facilities may
 keep objects alive that would normally be collectable. Also note that catching
-an exception with a ':keyword:`try`...\ :keyword:`except`' statement may keep
+an exception with a :keyword:`try`...\ :keyword:`except` statement may keep
 objects alive.
 
 Some objects contain references to "external" resources such as open files or
 windows.  It is understood that these resources are freed when the object is
 garbage-collected, but since garbage collection is not guaranteed to happen,
 such objects also provide an explicit way to release the external resource,
 usually a :meth:`!close` method. Programs are strongly recommended to explicitly
-close such objects.  The ':keyword:`try`...\ :keyword:`finally`' statement
-and the ':keyword:`with`' statement provide convenient ways to do this.
+close such objects.  The :keyword:`try`...\ :keyword:`finally` statement
+and the :keyword:`with` statement provide convenient ways to do this.
 
 .. index:: single: container