help in task 4

# 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(num):
    return len(num)

def num_courses(num):
    total_courses = 0
    for total in num:
        total_courses = total_courses + len(num[total])
    return total_courses

def courses(num):
    course_list = []
    for teacher in num:
        course_list.extend(num[teacher])
    return course_list

def most_courses(num):