_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

self = 1+a,2-a,3+a,1-a,2+a,3-a

    def _construct_planar_graph(self):
        pd = self.planar_diagram()
        g, duplicates, heights, first_edge = pd.as_networkx_extended()
    
        import planarity
    
        pg = planarity.PGraph(g)
        pg.embed_drawplanar()
        g = planarity.networkx_graph(pg)
    
    
        node_labels = {}
        xs = []
        ys = []
    
        nodes_by_height = {}
        node_xs_by_y = {}
        node_xs_ys = {}
        node_lefts_rights = {}
    
        for node, data in g.nodes(data=True):
>           y = data['pos']
                ^^^^^^^^^^^
E           KeyError: 'pos'

pyknotid/representations/representation.py:338: KeyError
----------------------------- Captured stdout call -----------------------------
Finding crossings

i = 0 / 97
3.0 crossings found

Simplifying: initially 6 crossings

-> 6 crossings after 1 runs
=========================== short test summary info ============================
FAILED tests/test_spacecurve.py::test_reconstructed_space_curve - KeyError: '...
========================= 1 failed, 17 passed in 0.74s =========================
