def METHOD_NAME(self):
    """ Tests tree-diff Extended distance. Cophenetic Compared"""
    t1 = Tree(example1_nw)
    t2 = Tree(example3_nw)
    difftable = ediff.treediff(t1, t2, attr1='name', attr2='name',
                               dist_fn=ediff.RF_DIST, support=False,
                               reduce_matrix=False,
                               extended=ediff.cc_distance,
                               jobs=1, parallel=None)
    self.assertEqual(sum([i[1] for i in difftable]), 863.9737020175473)