code: def bezout(a, b):
      
      if b == 0:
          return (1, 0)
      else:
          u, v = bezout(b, a % b)
          return (v, u - (a // b) * v)
docs: Bezout coefficients for a and b
  
      :param a,b: non-negative integers
      :complexity: O(log a + log b)