import ast


def get_nth_argument_name(arguments: ast.arguments, n: int) -> str:
    """Return the name of the nth positional argument, or Ɛ if out-of-range."""
    _arguments = arguments.args

    if len(_arguments) == 0:
        return ""

    if not (0 <= n < len(_arguments)):
        return ""

    return _arguments[n].arg