I did not understand where i am doing a mistake in this challenge

# The dictionary will be something like:
# {'Jason Seifer': ['Ruby Foundations', 'Ruby on Rails Forms', 'Technology Foundations'],
#  'Kenneth Love': ['Python Basics', 'Python Collections']}
#
# Often, it's a good idea to hold onto a max_count variable.
# Update it when you find a teacher with more classes than
# the current count. Better hold onto the teacher name somewhere
# too!
#
# Your code goes below here.

def most_classes(teachers):
    max_count = 0
    for teacher, courses in teachers.items():
        if max_count < len(courses):
            max_count = len(courses)
    return teacher