Refactored to use a single implementation for concept evaluation

tests/test_builtin_helpers.py

@@ -46,12 +46,11 @@ def test_i_can_use_expect_when_only_errors_1():
     sheerka = get_sheerka()
 
     items = [
-        ReturnValueConcept("who", False, None),
+        ReturnValueConcept("who", False, sheerka.new(BuiltinConcepts.ERROR)),
     ]
     res = core.builtin_helpers.expect_one(get_context(sheerka), items)
     assert not res.status
-    assert sheerka.isinstance(res.value, BuiltinConcepts.TOO_MANY_ERRORS)
-    assert res.value.body == items
+    assert res.value, items[0]
     assert res.parents == items