In [10]: Facet
Out[10]: yade.wrapper.Facet
In [11]: Facet()
Out[11]: <Facet instance at 0x562c25e860b0>
In [13]: Facet.area
Out[13]: <property at 0x7f96734e08b0>
In [14]: Facet().area
Out[14]: nan
In [17]: ak = Facet()
In [18]: ak
Out[18]: <Facet instance at 0x562c2584d8a0>
In [19]: ak.area
Out[19]: nan
====
In [1]: ak = Facet()
In [2]: ak
Out[2]: <Facet instance at 0x55a2935fceb0>
In [3]: ak.vertices
Out[3]: [Vector3(nan,nan,nan), Vector3(nan,nan,nan), Vector3(nan,nan,nan)]
In [4]: ak.vertices = [(0,0,0),(1,0,0),(0,0,1)]
In [5]: ak.vertices
Out[5]: [Vector3(0,0,0), Vector3(1,0,0), Vector3(0,0,1)]
In [6]: ak.area
Out[6]: 0.5
