[lib] XmlVisitor: fix types : str is mandatory

library/cadbiom/models/guard_transitions/translators/chart_xml.py

@@ -165,7 +165,7 @@ class XmlVisitor:
             else:
                 subel = etree.SubElement(self.current_element, properties[0])
                 attrname = properties[1]
-                attr = properties[2]
+                attr = [str(val) for val in properties[2]]
                 subel.attrib.update(dict(zip(attrname, attr)))
 
         # transitions
@@ -173,7 +173,7 @@ class XmlVisitor:
             properties = transition.accept(self)
             sub_tr = etree.SubElement(self.current_element, properties[0])
             attrname = properties[1]
-            attr = properties[2]
+            attr = [str(val) for val in properties[2]]
             sub_tr.attrib.update(dict(zip(attrname, attr)))
 
         self.current_element = save_macro