def most_common_employer_or_none(jobs):
    """Returns most common employer 
    from a list of jobs.

    Args:
        jobs ([Job]): List of job model objects

    Returns:
        Enum: most common Employer enum in list, or None if no Job in jobs has an employer set.
    """
    employers = [j.employer for j in jobs if j is not None]
    if len(employers) == 0:
        return None
    else:
        most_common = max(set(employers), key=employers.count)
        return most_common