'Used internally after parsing the header.'

def __init__(self, disposition, assocs):

    assert (len(disposition) == 1)
    self.disposition = disposition[0]
    self.assocs = dict(assocs)
    if ('filename*' in self.assocs):
        param = self.assocs['filename*']
        assert isinstance(param, ExtDispositionParm)
        self.assocs['filename*'] = parse_ext_value(param.value).string
