def convert_2d(subgrid_snapshots, shape, timesteps):
    """
    Utility to convert list of grids to list of 2d grids

    Args:
        subgrid_snapshots (List): List of subgrids
        shape (Tuple): Shape of 2d grid, e.g. (nFields, nx, ny)
        timesteps (Int): Number of timesteps

    Returns:
        List: List of converted subgrids
    """
    subgrid_snapshots_out = []
    for i, subgrid_snapshot in enumerate(subgrid_snapshots):
        subgrid_snapshots_out.append(subgrid_snapshot.reshape((shape[0],
                                                               shape[1],
                                                               shape[2],
                                                               timesteps)))
    return subgrid_snapshots_out