def METHOD_NAME(self):
    # Check if the user has at least uploaded a document or indicated an URL.
    if not (self.url or self.document or self.title):
        raise ValidationError(
            _('It is required to have at least a title, an uploaded document or indicate an '
              'URL.')
        )
    # Check for non-unicode characters
    if self.document:
        self.document.name = self.document.name.encode('ascii', 'ignore')