Fix sphinx docs broken after dependency hell

lib/tfw/fsm/fsm_base.py

@@ -23,6 +23,11 @@ class FSMBase(Machine, CallbackMixin):
     states, transitions = [], []
 
     def __init__(self, initial=None, accepted_states=None):
+        """
+        :param initial: which state to begin with, defaults to the last one
+        :param accepted_states: list of states in which the challenge should be
+                                considered successfully completed
+        """
         self.accepted_states = accepted_states or [self.states[-1].name]
         self.trigger_predicates = defaultdict(list)
         self.event_log = []

lib/tfw/fsm/linear_fsm.py

@@ -16,6 +16,9 @@ class LinearFSM(FSMBase):
     (0) --  step_next  --> (1) --  step_next  --> (2) --  step_next  --> (3) ...
     """
     def __init__(self, number_of_steps):
+        """
+        :param number_of_steps: how many states this FSM should have
+        """
         self.states = [State(name=str(index)) for index in range(number_of_steps)]
         self.transitions = []
         for state in self.states[:-1]: