def _separate(kw,splitter):
    """
    Returns string triplet: phone,negation (if any),keyword_w_args. If
    kw is not a keyword, returns '','',''.
    """
    matchobj=splitter.match(kw)
    if not matchobj:
        return None,None,None
    else:
        if matchobj.group(1): g1=matchobj.group(1)
        else: g1=''
        if matchobj.group(2): g2=matchobj.group(2)
        else: g2=''       
        return g1,g2,matchobj.group(3)