code: def _prioritize_plot_regions(region_bt, data, out_dir=None):
      
      max_plots = 1000
      max_size = 100 * 1000 # 100kb
      out_file = "%s-priority%s" % utils.splitext_plus(region_bt.fn)
      if out_dir:
          out_file = os.path.join(out_dir, os.path.basename(out_file))
      num_plots = 0
      if not utils.file_uptodate(out_file, region_bt.fn):
          with file_transaction(data, out_file) as tx_out_file:
              with open(tx_out_file, "w") as out_handle:
                  for r in region_bt:
                      if r.stop - r.start < max_size:
                          if num_plots < max_plots:
                              num_plots += 1
                              out_handle.write("%s\t%s\t%s\n" % (r.chrom, r.start, r.stop))
      return out_file
docs: Avoid plotting large numbers of regions due to speed issues. Prioritize most interesting.
  
      XXX For now, just removes larger regions and avoid plotting thousands of regions.
      Longer term we'll insert biology-based prioritization.