from typing import Dict
from typing import List


def _thread_levels_from_results(results: Dict) -> List[str]:
    """
    Gather the thread levels from the results dict.

    :param results: Dictionary of performance results.
    :return: List of thread levels.
    """
    # Sort as integers
    thread_levels = sorted(int(key) for key in results.keys() if key.isdigit())
    # Cast back to string
    return [str(entry) for entry in thread_levels]