import re


def clean(s):
    """ Get rid of any non-alphabetic character and clean up whitespace. """
     # Remove everything that isn't an alphabet character (only interested
     # in words, not numbers or punctuation).
    s = re.sub(r'[^a-zA-Z]', ' ', s)
    # Collapse whitespace in any amount or type (tabs, newlines, etc.) into
    # a single space.
    s = re.sub(r'\s+', ' ', s)
    return s