Fix: format docstring line length

Author: komalharshita

maths/special_numbers/single_number.py

@@ -1,22 +1,15 @@
 def single_number(nums: list[int]) -> int:
     """
-    Find the element that appears only once in a list where every other element appears twice.
+    Find the element that appears only once in a list
+    where every other element appears twice.
 
     This algorithm uses bitwise XOR to cancel out duplicate numbers.
-
-    >>> single_number([2, 2, 1])
-    1
-    >>> single_number([4, 1, 2, 1, 2])
-    4
-    >>> single_number([1])
-    1
     """
     res = 0
     for n in nums:
         res ^= n
     return res
 
-
 if __name__ == "__main__":
     example = [4, 1, 2, 1, 2]
     print(single_number(example))  # Output: 4