import re


def clean_html_from_string(raw_html):
    """ This function receives an HTML string of a text, and retrieves a clean string of its content.

    Args:
        raw_html: An HTML format text

    Returns:
        (string). A clean text string
    """
    if not raw_html:
        return None
    clean_r = re.compile('<.*?>')
    clean_text = re.sub(clean_r, '', raw_html)
    return clean_text