def test_len():
anm = NetworkModel()
""" default overlays are:
input, phy, _dependencies, graphics
"""
assert (len(anm) == 4)
anm.add_overlay("test")
assert (len(anm) == 5)
def test_init():
anm = NetworkModel()
print anm
def test_init():
anm = NetworkModel()
assert (anm.has_overlay(("phy")) is True)
assert (anm.has_overlay(("test")) is False)