input: Write a python function to determine if two numbers are coprime.
  assert is_coprime(34, 21) == True
  assert is_coprime(14, 21) == False
  assert is_coprime(17, 19) == True
  assert is_coprime(18, 24) == False
output: def is_coprime(a, b):
      def gcd(x, y):
          while y != 0:
              (x, y) = (y, x % y)
          return x
  
      return gcd(a, b) == 1