NW, (-1/2, 1/2) and the like). They were previously mapped to the wrong cell.staggered_access("E") would return the same thing as staggered_access("W")
did when called from the eastern-next cell). Now, when a field is declared
as STAGGERED_FLUX, it returns an accessor with a prefactor of -1 in that
case. The previous behavior where sign is not reversed is still useful when
e.g. storing sums (e.g. mean values) instead of differenes (e.g. finite
difference fluxes) on the staggered grid.staggered_vector_access returns a vector/tensor full of Access objects corresponding to the shape (index_shape[1:]) of the staggered field