What is the Pythonic way to implement a simple FSM?

Question

Yesterday I had to parse a very simple binary data file - the rule is, look for two bytes in a row that are both 0xAA, then the next byte will be a length byte, then skip 9 byte

Answer 1

I think the most pythonic way would by like what FogleBird suggested, but mapping from (current state, input) to a function which would handle the processing and transition.