code: def get_data(name=None):
      
      if name is None:
          files = []
          for fname in os.listdir(data_path):
              if (fname.endswith('.nii.gz')) or (fname.endswith('.jpg') or (fname.endswith('.csv'))):
                  fname = os.path.join(data_path, fname)
                  files.append(fname)
          return files
      else:
          datapath = None
          for fname in os.listdir(data_path):
              if (name == fname.split('.')[0]) or ((name+'slice') == fname.split('.')[0]):
                  datapath = os.path.join(data_path, fname)
  
          if datapath is None:
              raise ValueError('File doesnt exist. Options: ' , os.listdir(data_path))
          return datapath
docs: Get ANTsPy test data filename
  
      ANTsR function: `getANTsRData`
      
      Arguments
      ---------
      name : string
          name of test image tag to retrieve
          Options:
              - 'r16'
              - 'r27'
              - 'r64'
              - 'r85'
              - 'ch2'
              - 'mni'
              - 'surf'
      Returns
      -------
      string
          filepath of test image
  
      Example
      -------
      >>> import ants
      >>> mnipath = ants.get_ants_data('mni')