Added ModifyConcept function, and fixed 'isa' not working

tests/core/test_concept.py

@@ -198,6 +198,9 @@ def test_i_can_update_from():
         id="123456"
     ).def_prop("a", "10").def_prop("b", None)
 
+    # make sure origin is preserved
+    setattr(template, "##origin##", "digest")
+
     template.values[ConceptParts.BODY] = "value in body"
     template.values[ConceptParts.WHERE] = "value in where"
     template.values[ConceptParts.PRE] = "value in pre"
@@ -208,3 +211,4 @@ def test_i_can_update_from():
     concept = Concept().update_from(template)
 
     assert concept == template
+    assert getattr(concept, "##origin##") == "digest"