code: def write_stats(stats, fname, header=None):
      
      # Write stats output to file
  
      for bg in list(stats.values())[0].keys():
          f = open(fname.format(bg), "w")
          if header:
              f.write(header)
          
          stat_keys = sorted(list(list(stats.values())[0].values())[0].keys())
          f.write("{}\t{}\n".format("Motif", "\t".join(stat_keys)))
  
          for motif in stats:
              m_stats = stats.get(str(motif), {}).get(bg)
              if m_stats:
                  f.write("{}\t{}\n".format(
                      "_".join(motif.split("_")[:-1]),
                      "\t".join([str(m_stats[k]) for k in stat_keys])
                      ))
              else:
                  logger.warn("No stats for motif {0}, skipping this motif!".format(motif.id))
              #motifs.remove(motif)
          f.close()
  
      return
docs: write motif statistics to text file.