mark suds.mx.core.Core.node() as abstract

This function was never actually getting used as it is overridden in all
non-abstract mashaller classes, i.e. in both `Encoded` & `Literal`.

Its description also seemed to contain some content incorrectly copy/pasted from
suds.mx.core.Core.suspend().

README.rst

@@ -336,6 +336,9 @@ version 0.7 (development)
   * Reformatted.
   * Converted to a unicode string.
 
+* Marked ``suds.mx.core.Core.node()`` as abstract since this base class variant
+  is never actually used (both ``Encoded`` & ``Literal`` derived classes use a
+  different implmentation).
 * ``suds.binding.Binding`` converted to a new-style class.
 * ``suds.tostr()`` utility function may no longer silently eat internal Python
   exceptions like ``KeyboardInterrupt`` or ``SystemExit``.

suds/mx/core.py

@@ -21,7 +21,6 @@ Provides I{marshaller} core classes.
 from suds import *
 from suds.mx import *
 from suds.mx.appender import ContentAppender
-from suds.sax.element import Element
 from suds.sax.document import Document
 
 from logging import getLogger
@@ -78,12 +77,12 @@ class Core:
     def node(self, content):
         """
         Create and return an XML node.
-        @param content: The content for which processing has been suspended.
-        @type content: L{Object}
+        @param content: Content information for the new node.
+        @type content: L{Content}
         @return: An element.
         @rtype: L{Element}
         """
-        return Element(content.tag)
+        raise NotImplementedError
 
     def start(self, content):
         """