Add support for assignments, function calls and pure identifiers

smnp/ast/node/operator.py

@@ -112,4 +112,10 @@ class Operator(Node):
 
     @value.setter
     def value(self, value):
-        self[0] = value
+        self[0] = value
+
+    @classmethod
+    def withValue(cls, value, pos):
+        node = cls(pos)
+        node.value = value
+        return node