content: -- Task ID: HumanEval/13
  -- Assigned To: Author A
  
  -- Python Implementation:
  
  -- 
  -- 
  -- def greatest_common_divisor(a: int, b: int) -> int:
  --     """ Return a greatest common divisor of two integers a and b
  --     >>> greatest_common_divisor(3, 5)
  --     1
  --     >>> greatest_common_divisor(25, 15)
  --     5
  --     """
  --     while b:
  --         a, b = b, a % b
  --     return a
  -- 
  
  
  -- Haskell Implementation:
  
  -- Return a greatest common divisor of two integers a and b
  -- >>> greatest_common_divisor 3 5
  -- 1
  -- >>> greatest_common_divisor 25 15
  -- 5
  greatest_common_divisor :: Int -> Int -> Int
  greatest_common_divisor a b = ⭐ gcd ⭐ a b
  