class_docstr: A catalog that stores information about the datasets and how to obtain them.
  It contains a mapping from strings (which are names that identify a dataset,
  e.g. "imagenet1k") to a `dict` which contains:
      1) mapping of various data splits (train, test, val) to the data source
         (path on the disk whether a folder path or a filelist)
      2) source of the data (disk_filelist | disk_folder | disk_roi_annotations)
  The purpose of having this catalog is to make it easy to choose different datasets,
  by just using the strings in the config.
docstr: Check whether the data with ``name`` exists.
docstr_tok: ["Check","whether","the","data","with","``","name","``","exists","."]
code: def has_data(name):
      """
      Check whether the data with ``name`` exists.
      """
      data_found = name in VisslDatasetCatalog.__REGISTERED_DATASETS
      return data_found
  
imports: import json
  import logging
  import os
  from typing import List
  import numpy
  from iopath.common.file_io import g_pathmgr
  from vissl.data.datasets import get_coco_imgs_labels_info, get_voc_images_labels_info
  from vissl.utils.misc import get_json_data_catalog_file
  from vissl.utils.slurm import get_slurm_dir
label_desc: Use image node_id 8 for calling the VisslDatasetCatalog obj's underlying member method code with example usage: obj.has_data(name) and returns: data_found