'Validate API returned expected schema, and that the translated text
is different than the original string.'

def _validate_translation(self, source, result):

    if (not result):
        raise NotTranslated('Translation    API    returned    and    empty    response.')
    if PY2:
        result = result.encode('utf-8')
    if (result.strip() == source.strip()):
        raise NotTranslated('Translation    API    returned    the    input    string    unchanged.')
