:sig
String cli_arg(Request& context, String key, String default_value = "")

:see
>ob
>1_CLI
>cli_input

:content
Reads one value from the merged `cli_input(context)` parameter tree.

If the key is missing, or the resolved value is empty, `default_value` is returned.


For commands that need multiple values or typed reads, prefer calling `cli_input(context)` once and reading the returned `DValue` directly.

:example
String name = cli_arg(context, "name", "world");
print("hello ", name, "\n");