from collections import defaultdict

import string

def extract_popular(textstring):

"""

Input: string

Output: dictionary with counts for each character in a string

"""

d = defaultdict(int)

exclude = set(string.punctuation)

textstring = textstring.lower()

textstring = ''.join(ch for ch in textstring if ch not in exclude)

for c in textstring:

d[c] += 1

counts = [(d[c], c) for c in d]

counts.sort()

counts.reverse()

return counts

print(extract_popular("A man, a plan, a canal: Panama"))

print(extract_popular("Testing, attention please"))