Added doctests

maths/carmichael_number.py

@@ -13,6 +13,16 @@
 
 
 def gcd(a: int, b: int) -> int:
+    """
+
+    Examples:
+    >>> gcd(9, 3)
+    3
+
+    >>> gcd(2, 1)
+    1
+    """
+
     if a < b:
         return gcd(b, a)
     if a % b == 0:
@@ -21,6 +31,16 @@ def gcd(a: int, b: int) -> int:
 
 
 def power(x: int, y: int, mod: int) -> int:
+    """
+
+    Examples:
+    >>> power(2, 15, 3)
+    2
+
+    >>> power(5, 1, 30)
+    5
+    """
+
     if y == 0:
         return 1
     temp = power(x, y // 2, mod) % mod
@@ -31,6 +51,25 @@ def power(x: int, y: int, mod: int) -> int:
 
 
 def is_carmichael_number(n: int) -> bool:
+    """
+
+    Examples:
+    >>> is_carmichael_number(562)
+    False
+
+    >>> is_carmichael_number(561)
+    True
+
+    >>> is_carmichael_number(5.1)
+    Traceback (most recent call last):
+         ...
+    ValueError: Number 5.1 must instead be integer
+    """
+
+    if not isinstance(n, int):
+        msg = f"Number {n} must instead be integer"
+        raise ValueError(msg)
+
     b = 2
     while b < n:
         if gcd(b, n) == 1 and power(b, n - 1, n) != 1: