code: def _data_path(path=None, verbose=None):
      """Get path to local copy of EEG Physionet age Polysomnography dataset URL.
  
      This is a low-level function useful for getting a local copy of a
      remote Polysomnography dataset :footcite:`KempEtAl2000` which is available
      at PhysioNet :footcite:`GoldbergerEtAl2000`.
  
      Parameters
      ----------
      path : None | str
          Location of where to look for the data storing location.
          If None, the environment variable or config parameter
          ``PHYSIONET_SLEEP_PATH`` is used. If it doesn't exist, the "~/mne_data"
          directory is used. If the dataset is not found under the given path,
          the data will be automatically downloaded to the specified folder.
      %(verbose)s
  
      Returns
      -------
      path : list of Path
          Local path to the given data file. This path is contained inside a list
          of length one, for compatibility.
  
      References
      ----------
      .. footbibliography::
      """  # noqa: E501
      key = "PHYSIONET_SLEEP_PATH"
      name = "PHYSIONET_SLEEP"
      path = _get_path(path, key, name)
      return op.join(path, "physionet-sleep-data")
  
file_path: mne-python/mne/datasets/sleep_physionet/_utils.py
imports: import os
  import os.path
  import numpy
  from ...utils import _check_pandas_installed, _on_missing, _TempDir, verbose
  from ..utils import _downloader_params, _get_path
label_desc: Use image node_id 2 for calling a global function with example usage: _data_path(path, verbose) and returns: op