update

Task/Longest-string-challenge/Python/longest-string-challenge.py

@@ -1,10 +1,14 @@
 import fileinput
 
-# return len(a) - len(b) if positive, 0 otherwise
+# originally, return len(a) - len(b) if positive, 0 otherwise.
+# Observing that longer is used for its Boolean result,
+# and that '' is False, while any other string is True,
+# longer need only to return a after removing len(b) characters,
+# which is done without resorting to len().
 def longer(a, b):
-    while len(a) and len(b):
+    while a and b:
         a, b = a[1:], b[1:]
-    return len(a)
+    return a
 
 longest, lines = '', ''
 for x in fileinput.input():