TODO list
==============


* cnograph: 
    * mapback function. 
    * check the add_node and add_edge : seems that the shape of the node are not
        from the get_attribute
    * check carefully the +=, + operators and __radd__ 
* midas: remove functions: remove celltype or signal or cues
* midas: select functions


* create the sif with: [(x[0], x[2]['link'], x[1]) for x in list(c.edges_iter(data=True))]