Contact's name not showing in private messages

The following code is buggy:

    def _get_contact_name(self, contact_id):
        name = ""
        for contact in self.contacts_list:
            if contact["contactId"] is contact_id:
                name = contact["author"]["name"]
                if "alias" in contact:
                    name = contact["alias"]
                break
        return name

It's fixed by doing

    def _get_contact_name(self, contact_id):
        name = ""
        for contact in self.contacts_list:
-            if contact["contactId"] is contact_id:
+            if contact["contactId"] == contact_id:
                name = contact["author"]["name"]
                if "alias" in contact:
                    name = contact["alias"]
                break
        return name