Update pangram.py

Author: ikostan

pangram/pangram.py

@@ -1,2 +1,27 @@
-def is_pangram(sentence):
-    pass
+"""
+Pangram.
+
+You work for a company that sells fonts through their website. They'd like to show a
+different sentence each time someone views a font on their website. To give a
+comprehensive sense of the font, the random sentences should use all the letters
+in the English alphabet.
+
+They're running a competition to get suggestions for sentences that they can use.
+You're in charge of checking the submissions to see if they are valid.
+"""
+import string
+
+letters: str = string.ascii_lowercase
+
+
+def is_pangram(sentence: str) -> bool:
+    """
+    Verify that the random sentences uses all the letters in the English alphabet.
+
+    :param sentence: The sentence to check for pangram validity
+    :type sentence: str
+    :return: True if the sentence contains all 26 letters of the English alphabet, False otherwise
+    :rtype: bool
+    """
+    sentence = sentence.lower()
+    return all(char in letters for char in sentence if char.isalpha())