input: Write a python function to split a secret using a random prime and compute shares.
  assert len(split_secret(b'ABCDEFGH', 8, 5)) == 8
  assert len(split_secret(b'12345678', 6, 3)) == 6
  assert isinstance(split_secret(b'ABCDEFGH', 8, 5), list)
output: import random
  from sympy import nextprime
  
  def split_secret(secret, n, k):
      def get_random_coefficients(k):
          return [random.randint(1, 255) for _ in range(k - 1)]
  
      def polynomial(x, coefficients, secret):
          result = secret
          for i, coefficient in enumerate(coefficients):
              result = (result + coefficient * (x ** (i + 1))) % prime
          return result
  
      secret_int = int.from_bytes(secret, byteorder='big')
      prime = nextprime(secret_int)
      coefficients = get_random_coefficients(k)
  
      shares = [(i, polynomial(i, coefficients, secret_int)) for i in range(1, n + 1)]
      
      return shares