code: def read_id_list(filepath):
      
      if not filepath:
          return None
      id_list = []
      with open(filepath) as f:
          for line in f:
              line = line.rstrip()
              if not re.match('^[0-9]{8}$', line):
                  raise('Each line in whitelist or blacklist is expected '
                        'to contain an eight digit ID, and nothing else.')
              else:
                  id_list.append(line)
      return id_list
docs: Get project member id from a file.
  
      :param filepath: This field is the path of file to read.