Improved PyhtonEvaluator in order to use methods that need context

tests/non_reg/test_sheerka_non_reg.py

@@ -192,7 +192,7 @@ as:
         assert sheerka.isinstance(res[0].value, BuiltinConcepts.NOP)
 
     def test_i_can_recognize_concept_with_variable(self):
-        sheerka, context,  concept_foo, concept_hello = self.init_concepts(
+        sheerka, context, concept_foo, concept_hello = self.init_concepts(
             "foo",
             Concept(name="hello a").def_var("a"),
             create_new=True)
@@ -869,6 +869,35 @@ as:
         # assert res[0].status
         # assert isinstance(res[0].body, Concept)
 
+    def test_i_can_express_comparison(self):
+        definitions = [
+            "def concept one",
+            "def concept two",
+            "def concept three",
+            "def concept four",
+        ]
+
+        sheerka = self.init_scenario(definitions)
+
+        res = sheerka.evaluate_user_input("is_greater_than('some_prop', two, one)")
+        assert res[0].status
+
+        res = sheerka.evaluate_user_input("is_less_than('some_prop', two, three)")
+        assert res[0].status
+
+        res = sheerka.evaluate_user_input("get_concepts_weights('some_prop')")
+        assert res[0].status
+        assert res[0].body == {'1001': 1, '1002': 2, '1003': 3}
+
+        # test i use a concept to define relation
+        sheerka.evaluate_user_input("def concept a > b as is_greater_than('some_prop', a, b)")
+        res = sheerka.evaluate_user_input("eval four > three")
+        assert res[0].status
+
+        res = sheerka.evaluate_user_input("get_concepts_weights('some_prop')")
+        assert res[0].status
+        assert res[0].body == {'1001': 1, '1002': 2, '1003': 3, '1004': 4}
+
 
 class TestSheerkaNonRegFile(TestUsingFileBasedSheerka):
     def test_i_can_def_several_concepts(self):