'Returns True if given site has an associated site theme in database, returns False otherwise.
Note: DEFAULT_SITE_THEME is not considered as an associated site.
Args:
site (django.contrib.sites.models.Site): site object related to the current site.
Returns:
True if given site has an associated site theme in database, returns False otherwise.'

@staticmethod
def has_theme(site):

    return site.themes.exists()
