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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def generichash_blake2b_init(key=b'', salt=b'', person=b'', digest_size=crypto_generichash_BYTES):
 """ Create a new initialized blake2b hash state :param key: must be at most :py:data:`.crypto_generichash_KEYBYTES_MAX` long :type key: bytes :param salt: must be at most :py:data:`.crypto_generichash_SALTBYTES` long; will be zero-padded if needed :type salt: bytes :param person: must be at most :py:data:`.crypto_generichash_PERSONALBYTES` long: will be zero-padded if needed :type person: bytes :param digest_size: must be at most :py:data:`.crypto_generichash_BYTES_MAX`; the default digest size is :py:data:`.crypto_generichash_BYTES` :type digest_size: int :return: a initialized :py:class:`.Blake2State` :rtype: object """


    _checkparams(digest_size, key, salt, person)

    state = Blake2State(digest_size)

    # both _salt and _personal must be zero-padded to the correct length
    _salt = ffi.new("unsigned char []", crypto_generichash_SALTBYTES)
    _person = ffi.new("unsigned char []", crypto_generichash_PERSONALBYTES)

    ffi.memmove(_salt, salt, len(salt))
    ffi.memmove(_person, person, len(person))

    rc = lib.crypto_generichash_blake2b_init_salt_personal(state._statebuf,
                                                           key, len(key),
                                                           digest_size,
                                                           _salt, _person)
    ensure(rc == 0, 'Unexpected failure',
           raising=exc.RuntimeError)

    return state