def pbs_cove_allowfullscreen(apps, schema_editor):
    """
    Updates all existing all PBS COVE partner play embed codes to include
    'allowfullscreen'.
    """
    StacksEmbed = apps.get_model('wagtail_stacks_embed', 'StacksEmbed')
    for embed in StacksEmbed.objects.filter(service='pbs_cove'):
        embed_code = embed.embed_code.replace("'></iframe>",
            "' allowfullscreen></iframe>")
        embed.embed_code = embed_code
        embed.save()
