code: def make_fpfList(options, score_structure):
      
  
      # set variables
      fpf = options.fpf
      n = len([x[4] for x in score_structure if x[3] == '0'])   # Total no. of decoys
  
      # Default fpf values. We include 1, to ensure that the ef dictionary in the results dictionary objects contains
      # the total number of decoys in the set, which is required in the screener.find_best_ensemble method
      fpf_list = [0.0001, 0.001, 0.01, 0.05, 1]
  
      if fpf and fpf not in fpf_list:
          fpf_list.append(float(fpf))
  
      if not fpf:
          fpf = float(1) / n
          fpf_list.append(fpf)
  
      fpf_list.sort()
  
      return fpf_list
docs: aggregate default fpf values and user-defined fpf values where enrichment factor calculations will be attempted.
      :param options:
      :param score_structure:
      :return: