Finished working on the ISBN Verifier challenge

Author: sinanata

isbn-verifier/__pycache__/isbn_verifier.cpython-37.pyc

@@ -1,2 +1,13 @@
+import re
+
 def is_valid(isbn):
-    pass
+    isbn = isbn.replace("-", "").replace(" ", "").upper();
+    match = re.search(r'^(\d{9})(\d|X)$', isbn)
+    if not match:
+        return False
+
+    digits = match.group(1)
+    check_digit = 10 if match.group(2) == 'X' else int(match.group(2))
+
+    result = sum((i + 1) * int(digit) for i, digit in enumerate(digits))
+    return (result % 11) == check_digit