Unsure of where I'm going wrong, teachers.py step 5/5

# 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(teachers):
    count = 0
    for teacher in teachers:
        count += 1

    return count

def num_courses(courses):
    count = 0
    for i in courses:
        count += len(courses[i])
    return count

def courses(courses):
    count = []
    for i in courses:
        count += courses[i]
    return count

def most_courses(teacher):
    leader = 0
    teacherMost = ""
    for i in teacher:
        if len(teacher[i]) > leader:
            leader = len(teacher[i])
            teacherMost = i
    return teacherMost

def stats(teacher):
    stats = []
    for i in teacher:
        stats += [i, len(teacher[i])]

    return stats