Add some yml functionality implemented in the master branch

pycif/utils/yml.py

@@ -15,4 +15,16 @@ def ordered_load(stream, Loader=yaml.SafeLoader, object_pairs_hook=OrderedDict):
     OrderedLoader.add_constructor(
         yaml.resolver.BaseResolver.DEFAULT_MAPPING_TAG,
         construct_mapping)
+
+
+    # define custom tag handler
+    def join(loader, node):
+        seq = loader.construct_sequence(node)
+        return ''.join([str(i) for i in seq])
+    # end function join
+
+    # register the tag handler
+    OrderedLoader.add_constructor('!join', join)
+
+
     return yaml.load(stream, OrderedLoader)