Extract more contextual info from the words.

A property dictionary is now only to be considered equal to a word
when it shares at least one group, or neither has groups.

naive-nlu/tree_nlu/knowledge_evaluation.py

@@ -273,3 +273,21 @@ def integrate_information(knowledge_base, example):
     return tagged_with_ast(
         ast, elements,
         knowledge_ingestion[method](knowledge_base, elements, *args))
+
+def can_be_used_in_place(knowledge, token, minisegment):
+    if token not in knowledge.knowledge:
+        return False
+
+    info = knowledge.knowledge[token]
+    info_groups = info.get('groups', set())
+    minisegment_groups = minisegment.get('groups', set())
+
+    # Common group
+    if len(info_groups & minisegment_groups) > 0:
+        return True
+
+    # Neither has a group
+    elif len(info_groups) == 0 == len(minisegment_groups):
+        return True
+
+    return False