code: def display_list_by_prefix(names_list, starting_spaces=0):
    
    cur_prefix, result_lines = None, []
    space = " " * starting_spaces
    for name in sorted(names_list):
      split = name.split("_", 1)
      prefix = split[0]
      if cur_prefix != prefix:
        result_lines.append(space + prefix + ":")
        cur_prefix = prefix
      result_lines.append(space + "  * " + name)
    return "\n".join(result_lines)
docs: Creates a help string for names_list grouped by prefix.