'Compact serialization.
:rtype: bytes'

def to_compact(self):

    assert (len(self.signatures) == 1)
    assert ('alg' not in self.signature.header.not_omitted())
    return ((((b64.b64encode(self.signature.protected.encode('utf-8')) + '.') + b64.b64encode(self.payload)) + '.') + b64.b64encode(self.signature.signature))
