app.py

def adjust_state(state: State) -> None:
  ...

def process(val: int, state: Optional[State] = None) -> ProcessResult:
  ...
  # A functionality that assumes state to be passed in.
  assert state
  adjust_state(state)
  
def app():
  process(10)
  # ^ No typing errors here, no signals that process technically
  # requires a state object to be defined before called.