Add artifact with given framing to the environment.

        :param object artifact: Artifact to be added.

def add_artifact(self, artifact):
        '''Add artifact with given framing to the environment.

        :param object artifact: Artifact to be added.
        '''
        artifact.env_time = self.age
        self.artifacts.append(artifact)
        self._log(logging.DEBUG, "ARTIFACTS appended: '{}', length={}"
                  .format(artifact, len(self.artifacts)))