A Python class is generated for an ASN.1 OCTET STRING type only if the following are true:

If a class is generated, it will contain static methods for the BER encoding or decoding of the value.

Example ASN.1:

Os2 ::= OCTET STRING (SIZE(1..5))

Generated Python Class:

class Os2:
    @staticmethod
    def ber_decode(decbuf, explicit=True, impllen=None):
    ...

    @staticmethod
    def ber_encode(value, encbuf, explicit=True):
    ...

The value that is returned by the decode method or passed into the encode method is a Python bytearray. Also, for encode, the type of the value passed in may be a string. In this case, the ordinal bytes of the characters are encoded.

See the BER encode/decode methods for information on how to call these methods.