Direct which class should be used based on the director
     qualifier.

def description_director(**kwargs):
    """Direct which class should be used based on the director
     qualifier.
    """
    description_type = {'physical': DCFormat}
    qualifier = kwargs.get('qualifier')
    # Determine the type of element needed, based on the qualifier.
    element_class = description_type.get(qualifier, DCDescription)
    # Create the element object of that element type.
    element = element_class(
        qualifier=qualifier,
        content=kwargs.get('content'),
    )
    return element