text: function is_tagged_list(stmt, the_tag) {
      return is_pair(stmt) && head(stmt) === the_tag;
  }
  function is_name(stmt) {
      return is_tagged_list(stmt, "name");
  }
  function name_of_name(stmt) {
      return head(tail(stmt));
  }
  
  const my_name_statement = parse("x;");
  display(is_name(my_name_statement));
  display(name_of_name(my_name_statement));