@classmethod<EOL><INDENT>def _ensure_frames(cls, documents):<DEDENT>
frames = []<EOL>for document in documents:<EOL><INDENT>if not isinstance(document, Frame):<EOL><INDENT>frames.append(cls(document))<EOL><DEDENT>else:<EOL><INDENT>frames.append(document)<EOL><DEDENT><DEDENT>return frames<EOL>
Ensure all items in a list are frames by converting those that aren't.