import re


def strip_text(text):

    """
    strips out all non alphabetic characters from a string,
    lower cases it, and removes extra whitespace characters.
    """

    text = text.lower()
    text = re.sub("_", " ", text)
    text = re.sub("[^A-Za-z0-9 ]", "", text)
    text = re.sub("\s+", " ", text)
    text = text.strip()
    return(text)