Stringpopulation_in_descending order

The program returns a sorted list of the letters in that string from most popular to least popular.
eg:
input:                                                         output:
"A man, a plan, a canal: Panama"	[(10, 'a'), (6, ' '), (4, 'n'), (2, 'p'), (2, 'm'), (2, 'l'), (1, 'c')]
"Testing, attention please."	[(5, 't'), (4, 'e'), (3, 'n'), (2, 's'), (2, 'i'), (2, 'a'), (2, ' '), (1, 'p'), (1, 'o'), (1, 'l'), (1, 'g')]

Author: cadwellh5

stringPopulation

@@ -0,0 +1,19 @@
+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"))