def strip_prefixes(s, prefixes=prefixes):
    """
    Return the `s` string with any of the string in the `prefixes` set
    striped from the left. Normalize and strip spaces.

    For example:
    >>> s = 'by AND for the Free Software Foundation'
    >>> strip_prefixes(s) == 'the Free Software Foundation'
    True
    """
    s = s.split()
    while s and s[0].lower().strip().strip('.,') in prefixes:
        s = s[1:]
    return u' '.join(s)
