Returns a list of tuples. Each tuple contains two elements (parent, child) for each edge.

        Examples
        --------
        >>> reader = XBNReader('xbn_test.xml')
        >>> reader.get_edges()
        [('a', 'b'), ('a', 'c'), ('b', 'd'), ('c', 'd'), ('c', 'e')]

def get_edges(self):
        """
        Returns a list of tuples. Each tuple contains two elements (parent, child) for each edge.

        Examples
        --------
        >>> reader = XBNReader('xbn_test.xml')
        >>> reader.get_edges()
        [('a', 'b'), ('a', 'c'), ('b', 'd'), ('c', 'd'), ('c', 'e')]
        """
        return [(arc.get('PARENT'), arc.get('CHILD')) for arc in self.bnmodel.find('STRUCTURE')]