task: metadata: install: pip install -e .[dev]
patch: diff --git a/hescorehpxml/hpxml3.py b/hescorehpxml/hpxml3.py
index 9a227e76..2c84e53c 100644
--- a/hescorehpxml/hpxml3.py
+++ b/hescorehpxml/hpxml3.py
@@ -66,10 +66,11 @@ class HPXML3toHEScoreTranslator(HPXMLtoHEScoreTranslatorBase):
             wall = self.xpath(
                 b,
                 '//h:Wall[h:SystemIdentifier/@id=$kneewallid][h:AtticWallType="knee wall"]',
-                raise_err=True,
+                raise_err=False,
                 kneewallid=kneewall_idref
             )
-            knee_walls.append(wall)
+            if wall is not None:
+                knee_walls.append(wall)
 
         return knee_walls
 

problem_statement: Update input validation
[new input validation rules](https://docs.google.com/spreadsheet/pub?key=0Aqq3Ugm1VCSwdE13bWsxNTRVaE54c2N2LWFBd3h6TXc&single=true&gid=1&output=html)
Check attic wall type when getting knee walls
When getting attic knee walls, this [method](https://github.com/NREL/hescore-hpxml/blob/master/hescorehpxml/hpxml3.py#L63-L74) expects all attic `AttachedToWall` fields to be knee walls, and throws an error when a different wall type is inputted (such as gable walls):

```ERROR:ElementNotFoundError:Can't find element Building///Wall[SystemIdentifier/@id=$kneewallid][AtticWallType="knee wall"] with args {'kneewallid': 'Surface_16'}```
repo: NREL/hescore-hpxml
test_cmd: pytest --no-header -rA --tb=line --color=no -p no:cacheprovider -W ignore::DeprecationWarning
test_patch: diff --git a/tests/test_translation.py b/tests/test_translation.py
index 8287a01b..dab1f7eb 100644
--- a/tests/test_translation.py
+++ b/tests/test_translation.py
@@ -6,6 +6,7 @@ import os
 import unittest
 import datetime as dt
 from lxml import etree, objectify
+from lxml.builder import ElementMaker
 from hescorehpxml import HPXMLtoHEScoreTranslator, main
 from hescorehpxml.exceptions import TranslationError, InputOutOfBounds, ElementNotFoundError
 import io
@@ -65,8 +66,7 @@ class ComparatorBase(object):
         return self.translator.xpath(self.translator.hpxmldoc, xpathexpr, *args, **kwargs)
 
     def element_maker(self):
-        E = objectify.ElementMaker(
-            annotate=False,
+        E = ElementMaker(
             namespace=self.translator.ns['h'],
             nsmap=self.translator.ns
         )
@@ -939,6 +939,30 @@ class TestOtherHouses(unittest.TestCase, ComparatorBase):
         self.assertEqual(resp['building']['zone']['zone_roof'][0]['ceiling_assembly_code'], 'ecwf00')
         self.assertAlmostEqual(resp['building']['zone']['zone_roof'][0]['roof_area'], 1400.0)
 
+    def test_gable_wall_ignore(self):
+        tr = self._load_xmlfile('hescore_min_v3')
+        E = self.element_maker()
+        wall1 = self.xpath('//h:Wall[1]')
+        wall2 = deepcopy(wall1)
+        wall1type = wall1.find(tr.addns('h:WallType'))
+        wall1type.addnext(E.Area('100'))
+        wall2type = wall2.find(tr.addns('h:WallType'))
+        wall2type.addnext(E.Area('20'))
+        # change the system id
+        sysid = wall2.find(tr.addns('h:SystemIdentifier'))
+        sysid.attrib['id'] = 'wall2'
+        # and the insulation id
+        ins_sysid = wall2.xpath('h:Insulation/h:SystemIdentifier', namespaces=tr.ns)[0]
+        ins_sysid.attrib['id'] = 'wall2ins'
+        wall1.addnext(wall2)
+        sysid.addnext(E.InteriorAdjacentTo('attic - vented'))
+        sysid.addnext(E.ExteriorAdjacentTo('outside'))
+        att_to_roof = self.xpath('//h:Attic/h:AttachedToRoof')
+        att_to_roof.addnext(E.AttachedToWall(idref='wall2'))
+
+        resp = tr.hpxml_to_hescore()
+        assert resp['building']['zone']['zone_roof'][0]['roof_area'] == 1200
+
     def test_wall_construction_ps_low_r(self):
         """
         Unit test for #47
@@ -2485,11 +2509,11 @@ class TestHEScore2019Updates(unittest.TestCase, ComparatorBase):
 
         window3_frametype = self.xpath('//h:Window[h:SystemIdentifier/@id="window3"]/h:FrameType')
         window3_frametype.clear()
-        window3_frametype.append(E.Aluminum(E.ThermalBreak(True)))
+        window3_frametype.append(E.Aluminum(E.ThermalBreak("true")))
 
         window4_frametype = self.xpath('//h:Window[h:SystemIdentifier/@id="window4"]/h:FrameType')
         window4_frametype.clear()
-        window4_frametype.append(E.Aluminum(E.ThermalBreak(True)))
+        window4_frametype.append(E.Aluminum(E.ThermalBreak("true")))
         window4_frametype.getparent().append(E.GlassType('low-e'))
 
         d = tr.hpxml_to_hescore()
@@ -2519,11 +2543,11 @@ class TestHEScore2019Updates(unittest.TestCase, ComparatorBase):
 
         window3_frametype = self.xpath('//h:Window[h:SystemIdentifier/@id="window3"]/h:FrameType')
         window3_frametype.clear()
-        window3_frametype.append(E.Aluminum(E.ThermalBreak(True)))
+        window3_frametype.append(E.Aluminum(E.ThermalBreak("true")))
 
         window4_frametype = self.xpath('//h:Window[h:SystemIdentifier/@id="window4"]/h:FrameType')
         window4_frametype.clear()
-        window4_frametype.append(E.Aluminum(E.ThermalBreak(True)))
+        window4_frametype.append(E.Aluminum(E.ThermalBreak("true")))
         window4_frametype.getparent().append(E.GlassType('low-e'))
 
         d_v3 = tr_v3.hpxml_to_hescore()