import time


def filter_blobs_by_modification_time(l: list, ref: float, after: bool = True):
    """Filters blobs by modification time.
    - `after` == True -> blob.updated >= ref
    - `after` == False -> blob.updated < ref"""
    return [blob for blob in l if not((time.mktime(blob.updated.timetuple()) >= ref) != after)]