Counting the number of items in the Python list

num = [1,2,2,3,3,4,4,4,4,4]

# # for statement
for n in num:
    print(n)

# # dictionary
d = { 'a': 1, 'b': 2 }

# # exist or not exist in a dictionary 
print('a' in d) # True
print('c' in d) # False
print('c' not in d) # True

# # set k-v to a dict
d['c'] = 3
print('c' in d) # True

# # if-else statement
if ('c' not in d):
    print('c is not exist in a dict')
else:
    # # get a value from a dict
    print(d['c']) # 3

# # increment
d['c'] += 1
print(d['c']) # 4