def get(self, key, host=None):
"""Return resource values without recording a dependency."""
if host is not None:
results = []
for root, values in list(self.resources.get(key, {}).items()):
if root.component.host is host:
results.extend(values)
else:
results = flatten(list(self.resources.get(key, {}).values()))
return results
def test_flatten():
assert [1, 2, 3, 4] == flatten([[1, 2], [3, 4]])