from datetime import datetime


def get_greeting_message() -> str:
    """
    Returns a greeting message.

    :return: Greeting message in string form
    """

    # Get the current time.
    hour = datetime.now().hour

    # Decide on a greeting phrase based on the current time.
    greeting_message = ''
    if 5 <= hour <= 11:
        greeting_message = 'Günaydın'
    elif 12 <= hour <= 15:
        greeting_message = 'Tünaydın'
    elif 16 <= hour <= 20:
        greeting_message = 'İyi akşamlar'
    elif 20 <= hour <= 24 or 0 <= hour <= 4:
        greeting_message = 'İyi geceler'
    else:
        greeting_message = 'İyi boyutlar arası zamanlar'

    # Return the greeting.
    return greeting_message