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Python Python Collections (2016, retired 2019) Dictionaries Teacher Stats

task 3 courses()

What is wrong with this? I am getting a TypeError: unhashable list. I tried on my PC and it works fine.

teachers.py
# 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(courses):
    counter = 0
    for teacher in courses.keys():
        counter += 1
    return counter

def num_courses(courses):
    counter = 0
    for i in courses:
        list1 = courses[i]
        for i in list1:
            counter += 1
    return counter

def courses(dict):
    total = []
    for i in dict.values():
        total.append(i)
    return total

1 Answer

With append(i), you're inserting 'i' at the end of the total list. You want extend() or += instead, which would return a new list.