Can't figure out step five

# The dictionary will look something like:
# {'Andrew Chalkley': ['jQuery Basics', 'Node.js Basics'],
#  'Kenneth Love': ['Python Basics', 'Python Collections']}
#
# Each key will be a Teacher and the value will be a list of courses.
#
# Your code goes below here.
def num_teachers(arg):
    count = 0 
    for item in arg.keys():
        count += 1
    return count

def num_courses(arg):
    count = 0
    for course in arg.values():
        for i in course:
            count += 1
    return count

def courses(arg):
    course_list = []
    for course in arg.values():
        for i in course:
            course_list.append(i)
    return course_list

def most_courses(arg):
    max_count = 0
    for teacher in arg:
        count = 0
        for course in teacher:
            count += 1
        if count > max_count:
            max_teacher = teacher
            count = max_count
    return teacher

def stats(arg):
    teacher_list = []
    return teacher_list