Returns True if densities are almost identical.

    Closeness is measured with the metric Fubini-Study angle.

def densities_close(rho0: Density, rho1: Density,
                    tolerance: float = TOLERANCE) -> bool:
    """Returns True if densities are almost identical.

    Closeness is measured with the metric Fubini-Study angle.
    """
    return vectors_close(rho0.vec, rho1.vec, tolerance)