Correct bug in Gml Lod

imports/geometry/citygml.py

@@ -23,7 +23,7 @@ class CityGml:
   """
   def __init__(self, path):
     self._city = None
-    self._lod = 0
+    self._lod = None
     self._lod1_tags = ['lod1Solid', 'lod1MultiSurface']
     self._lod2_tags = ['lod2Solid', 'lod2MultiSurface', 'lod2MultiCurve']
     self._lower_corner = None

unittests/test_construction_factory.py

@@ -28,6 +28,7 @@ class TestConstructionFactory(TestCase):
     file_path = (self._example_path / file).resolve()
     self._city = GeometryFactory('citygml', path=file_path).city
     self.assertIsNotNone(self._city, 'city is none')
+    self.assertIsNotNone(self._city.level_of_detail.geometry, 'wrong construction level of detail')
     return self._city
 
   @staticmethod