code: def default_motifs():
      
      config = MotifConfig()
      d = config.get_motif_dir()
      m = config.get_default_params()['motif_db']
  
      if not d or not m:
          raise ValueError("default motif database not configured")
  
      fname = os.path.join(d, m)
      with open(fname) as f:
          motifs = read_motifs(f)
      
      return motifs
docs: Return list of Motif instances from default motif database.