import collections
arr = ['a', 'a', 'b', 'b', 'b', 'c']
# set the elements frequencies using Counter class
elements_count = collections.Counter(arr)
# printing the element and the frequency
for key, value in elements_count.items():
print(f"{key}: {value}")
# output
# a: 2
# b: 3
# c: 1
data = 'hello world'
# set the elements frequencies using Counter class
elements_count = collections.Counter(data)
# printing the element and the frequency
print(elements_count)