Dissapearing Vertex Property Value


I'm having problems wrapping my head around this behaviour:

g = gt.Graph()
g.vp['name_num'] = g.new_vp('object')
print(g.vp.name_num[0]) # None
g.vp.name_num[0] = [('a', 1)]
print(g.vp.name_num[0]) # [('a', 1)]
g.vp.name_num[0] = g.vp.name_num[0].append(('b', 2))
print(g.vp.name_num[0]) # None

This is perfectly normal and expected behavior, since the append() method
returns None, which you are assigning to the property value.