def calculateBoxInertia(mass, size):
    """Returns upper diagonal of inertia tensor of a box as tuple.

    Args:
      mass(float): The box' mass.
      size(iterable): The box' size.

    Returns:
      : tuple(6)

    """
    i = mass / 12
    ixx = i * (size[1] ** 2 + size[2] ** 2)
    ixy = 0
    ixz = 0
    iyy = i * (size[0] ** 2 + size[2] ** 2)
    iyz = 0
    izz = i * (size[0] ** 2 + size[1] ** 2)
    return ixx, ixy, ixz, iyy, iyz, izz