def update_gender_count(gender, movie_id, movie_map):
    """Given gender, movieID, and a dictionary, returns an updated dictionary
    reflecting an increase in the gender count for the input gender.

    Parameters:
        gender: a string that is either 'female_count' or 'male_count'.
        movie_id: a string representing the identification code for a movie in
        the dataset.
        movie_map: a dictionary mapping from genre to release year to gender
        count.

    Returns:
        movie_map: an updated version of the input dictionary reflecting an
        increase in the gender count for the input gender.
    """

    # Determines old gender count
    gender_count = movie_map[movie_id][gender]

    # Creates a new mapping for gender count where the count increases by one
    movie_map[movie_id][gender] = gender_count + 1

    return movie_map