A turnstyle is a gate/barrier with a rotating bar that allows one person at a time to pass through after depositing a token. It has two states, open and locked.
When open, pushing against the bar will rotate it and allow one person to pass through, returning the bar to the locked state.
When locked, depositing a token will unlock the bar, i. e. put it in the open state.
Pushing when locked does nothing (the bar will not move); and depositng a token when open does nothing.

a. Draw the Finite State Diagram of this system (i. e. represent and label the states; show the output(s) associated with each state; and show the transitions associated with the possible values of the input(s)
b. Construct the truth table showing what transitions occur from each state for all possible values of all inputs.