<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def dump_normals(dataset_dir, data_dir, dataset, root=None, compress=True):
 """dump vtkjs normal vectors"""

    if root is None:
        root = {}
    normals = dataset.GetPointData().GetNormals()
    if normals:
        dumped_array = dump_data_array(dataset_dir, data_dir, normals, {}, compress)
        root['pointData']['activeNormals'] = len(root['pointData']['arrays'])
        root['pointData']['arrays'].append({'data': dumped_array})