code: def create_rois_mask(roislist, filelist):
      
      roifiles = []
  
      for roi in roislist:
          try:
              roi_file = search_list(roi, filelist)[0]
          except Exception as exc:
              raise Exception('Error creating list of roi files. \n {}'.format(str(exc)))
          else:
              roifiles.append(roi_file)
  
      return binarise(roifiles)
docs: Look for the files in filelist containing the names in roislist, these files will be opened, binarised
      and merged in one mask.
  
      Parameters
      ----------
      roislist: list of strings
          Names of the ROIs, which will have to be in the names of the files in filelist.
  
      filelist: list of strings
          List of paths to the volume files containing the ROIs.
  
      Returns
      -------
      numpy.ndarray
          Mask volume