'Expand insserv variables.'

def _InsservExpander(self, facilities, val):

    expanded = []
    if val.startswith('$'):
        vals = facilities.get(val, [])
        for v in vals:
            expanded.extend(self._InsservExpander(facilities, v))
    elif val.startswith('+'):
        expanded.append(val[1:])
    else:
        expanded.append(val)
    return expanded
