def timestamp_update(sender, frames):
        """
        Timestamp the modified field for all documents. This method should be
        bound to a frame class like so:

        ```
        MyFrameClass.listen('update', MyFrameClass.timestamp_update)
        ```
        """
        for frame in frames:
            frame.modified = datetime.now(timezone.utc)
def timestamp_update ( sender , frames ) : for frame in frames : frame . modified = datetime . now ( timezone . utc )
Timestamp the modified field for all documents. This method should be
        bound to a frame class like so:

        ```
        MyFrameClass.listen('update', MyFrameClass.timestamp_update)
        ```