def _parse_qs(qs, keep_blank_values=0, strict_parsing=0, encoding='utf-8'):
    """Parse a query given as a string argument.

    Arguments:
    qs: URL-encoded query string to be parsed

    keep_blank_values: flag indicating whether blank values in
        URL encoded queries should be treated as blank strings.  A
        true value indicates that blanks should be retained as blank
        strings.  The default false value indicates that blank values
        are to be ignored and treated as if they were  not included.

    strict_parsing: flag indicating what to do with parsing errors. If
        false (the default), errors are silently ignored. If true,
        errors raise a ValueError exception.

    Returns a dict, as G-d intended.
    """
    pairs = [s2 for s1 in qs.split('&') for s2 in s1.split(';')]
    d = {}
    for name_value in pairs:
        if not name_value and not strict_parsing:
            continue
        nv = name_value.split('=', 1)
        if len(nv) != 2:
            if strict_parsing:
                raise ValueError('bad query field: %r' % (name_value,))
            # Handle case of a control-name with no equal sign
            if keep_blank_values:
                nv.append('')
            else:
                continue
        if len(nv[1]) or keep_blank_values:
            name = unquote_plus(nv[0], encoding, errors='strict')
            value = unquote_plus(nv[1], encoding, errors='strict')
            if name in d:
                if not isinstance(d[name], list):
                    d[name] = [d[name]]
                d[name].append(value)
            else:
                d[name] = value
    return d
Parse a query given as a string argument.

    Arguments:
    qs: URL-encoded query string to be parsed

    keep_blank_values: flag indicating whether blank values in
        URL encoded queries should be treated as blank strings.  A
        true value indicates that blanks should be retained as blank
        strings.  The default false value indicates that blank values
        are to be ignored and treated as if they were  not included.

    strict_parsing: flag indicating what to do with parsing errors. If
        false (the default), errors are silently ignored. If true,
        errors raise a ValueError exception.

    Returns a dict, as G-d intended.
    
cherrypy/lib/httputil.py