Returns True if states are almost identical.

    Closeness is measured with the metric Fubini-Study angle.

def states_close(state0: State, state1: State,
                 tolerance: float = TOLERANCE) -> bool:
    """Returns True if states are almost identical.

    Closeness is measured with the metric Fubini-Study angle.
    """
    return vectors_close(state0.vec, state1.vec, tolerance)