code: def _merge_extra_filerefs(*args):
      '''
      Takes a list of filerefs and returns a merged list
      '''
      ret = []
      for arg in args:
          if isinstance(arg, six.string_types):
              if arg:
                  ret.extend(arg.split(','))
          elif isinstance(arg, list):
              if arg:
                  ret.extend(arg)
      return ','.join(retf _merge_extra_filerefs(*args):
      '''
      Takes a list of filerefs and returns a merged list
      '''
      ret = []
      for arg in args:
          if isinstance(arg, six.string_types):
              if arg:
                  ret.extend(arg.split(','))
          elif isinstance(arg, list):
              if arg:
                  ret.extend(arg)
      return ','.join(ret)
docs: Takes a list of filerefs and returns a merged list