code: public CommandLine getParent() {
          CommandSpec parent = getCommandSpec().parent();
          return parent == null ? null : parent.commandLine();
      }
docs: Returns the command that this is a subcommand of, or {@code null} if this is a top-level command.
  @return the command that this is a subcommand of, or {@code null} if this is a top-level command
  @see #addSubcommand(String, Object)
  @see Command#subcommands()
  @since 0.9.8