code: def fetch():
      
      doi = '10.7910/DVN/VBSI4A'
      
      for component in ['dust', 'err']:
          requirements = {'filename': 'PG_{}_4096_ngp.fits'.format(component)}
          local_fname = os.path.join(
              data_dir(),
              'pg2010', 'PG_{}_4096_ngp.fits'.format(component))
          print('Downloading P&G (2010) {} data file to {}'.format(
              component, local_fname))
          fetch_utils.dataverse_download_doi(
              doi,
              local_fname,
              file_requirements=requirements)
docs: Downloads the Peek & Graves (2010) dust map, placing it in
      the data directory for :obj:`dustmap`.