def get_most_frequent_letter(message):
    """Return the most frequent letter in the given message dictionary"""
    most_freq_value = 0
    most_freq_index = None
    for letter in message:
        if message[letter] >= most_freq_value:
            most_freq_value = message[letter]
            most_freq_index = letter
    return most_freq_index, most_freq_value