I can now use keyword in concept definition and parsing

tests/parsers/test_SyaNodeParser.py

@@ -34,6 +34,7 @@ cmap = {
     "foo bar": Concept("foo bar(a)").def_var("a"),
     "long infixed": Concept("a long infixed b").def_var("a").def_var("b"),
     "twenties": Concept("twenties", definition="'twenty' (one|two)=unit").def_var("unit"),
+    "is a concept": Concept("c is a concept").def_var("c"),
 }
 
 
@@ -1013,6 +1014,8 @@ class TestSyaNodeParser(TestUsingMemoryBasedSheerka):
         ]),
         ("function(suffixed x$!#)", False, [
             SCWC("function(", ")", CNC("suffixed", 2, 7, a="x$!#"))]),
+        ("one is a concept", True, [CNC("is a concept", c="one")]),
+        ("a is a concept", False, [CNC("is a concept", c=UTN("a"))]),
     ])
     def test_i_can_parse_when_one_result(self, text, expected_status, expected_result):
         sheerka, context, parser = self.init_parser()
@@ -1142,3 +1145,4 @@ class TestSyaNodeParser(TestUsingMemoryBasedSheerka):
 
         assert not res.status
         assert sheerka.isinstance(res.body, BuiltinConcepts.IS_EMPTY)
+