Guesses entity type when Content-Type header is missing.
        Since Content-Type is not strictly required, some servers leave it out.

def __looks_like_html(response):
        """Guesses entity type when Content-Type header is missing.
        Since Content-Type is not strictly required, some servers leave it out.
        """
        text = response.text.lstrip().lower()
        return text.startswith('<html') or text.startswith('<!doctype')