Problem writing graph in mac

What steps will reproduce the problem?
1. Create digraph: g = yapgvb.Digraph(fileName)
2. Construct the graph, add nodes and edges (g.add_node(...), ...)
3. Write graph: g.write(fileName)

What is the expected output? : A dot file with the graph

What do you see instead? No dot file and the following message:

********************************************************************************
Function:  write at /Library/Python/2.5/site-packages/yapgvb/_yapgvb_py.py:137
Calling:   CGraph.write(self, output_stream_or_filename)
           ('/Library/Python/2.5/site-packages/yapgvb/__init__.py', 233, 'write')
NotImplementedError: 
    Args:
        <Digraph "/Users/camilo/temp/graph.dot"> (<class 'yapgvb.Digraph'>)
        <open file '/Users/camilo/temp/graph.dot', mode 'w' at 0x104d380> (<type 'file'>)
    No keywords.
Traceback (most recent call last):
  File "/Users/camilo/Tools/ODS/ods2graph.py", line 289, in <module>
    gModel.WriteGraph()
  File "/Users/camilo/Tools/ODS/Model.py", line 608, in WriteGraph
    g.write(self.fileName)            
  File "/Library/Python/2.5/site-packages/yapgvb/__init__.py", line 233, in write
    CGraph.write(self, output_stream_or_filename)
  File "/Library/Python/2.5/site-packages/yapgvb/_yapgvb_py.py", line 59, in fc
    raise NotImplementedError("You are using the pure-Python experimental backend.  A lot of 
things are not implemented yet.")
NotImplementedError: You are using the pure-Python experimental backend.  A lot 
of things are 
not implemented yet.

What version of the product are you using? On what operating system?
yapgvb 1.2.0 
Mac OS X 10.5.8

Please provide any additional information below.

installed from yapgvb-1.2.0-source.tar (link in yapgvb page for Macintosh 
version)
Original issue reported on code.google.com by camilo.l...@gmail.com on 26 Nov 2009 at 1:27
DTM05 / yapgvb

Problem writing graph in mac #13
