code: def get_data_home(data_home=None):
      """Get the home data directory.
  
      By default the data dir is set to a folder named 'astroML_data'
      in the user home folder.
  
      Alternatively, it can be set by the 'ASTROML_DATA' environment
      variable or programatically by giving an explit folder path. The
      '~' symbol is expanded to the user home folder.
  
      If the folder does not already exist, it is automatically created.
      """
      import os
  
      if data_home is None:
          data_home = os.environ.get(
              "ASTROML_DATA", os.path.join("~", "astroML_data")
          )
      data_home = os.path.expanduser(data_home)
      if not os.path.exists(data_home):
          os.makedirs(data_home)
      return data_home
  
imports: from .download import download_with_progress_bar
  from .sql_query import sql_query
  from .cas_query import *
  from .sdss_fits import sdss_fits_url, sdss_fits_filename, SDSSfits
label_desc: Use image node_id 1 for calling a global function with example usage: get_data_home(data_home) and returns: data_home