IGraph::FileWrite IGraph::FileRead NoMethodError: Method not available on OSX

[arikan]

Thanks for the great wrapper, it works quite well.

But file reading and file writing methods do not work on Mac OS X, any recommendations? When I try this, I got an error:

g = IGraph::FileRead.read_graph_graphml "/Users/arikan/mynetwork.graphml"

NoMethodError: Method not available on OSX
        from (irb):11:in `read_graph_graphml'
        from (irb):11
        from :0