Removes the @about key from the `obj` dict if that value refers to the
    dict's '@id'

def _cull_redundant_about(obj):
    """Removes the @about key from the `obj` dict if that value refers to the
    dict's '@id'
    """
    about_val = obj.get('@about')
    if about_val:
        id_val = obj.get('@id')
        if id_val and (('#' + id_val) == about_val):
            del obj['@about']