input: Write a function to generate an RSA public/private key pair and save them to files named 'public.pem' and 'private.pem' respectively. If the function executes successfully, it should generate the key pair without returning any value.
  from Crypto.PublicKey import RSA
  
  def generate_key_pair():
      key = RSA.generate(2048)
      pub_key = key.publickey().export_key().decode()
      with open('public.pem', 'w') as file:
          file.write(pub_key)
      
      priv_key = key.export_key().decode()
      with open('private.pem', 'w') as file:
          file.write(priv_key)
  
  generate_key_pair()
  
  assert generate_key_pair() == None
  assert 'public.pem' in os.listdir()
  assert 'private.pem' in os.listdir()
output: 
  def generate_key_pair():
      key = RSA.generate(2048)
      pub_key = key.publickey().export_key().decode()
      with open('public.pem', 'w') as file:
          file.write(pub_key)
      
      priv_key = key.export_key().decode()
      with open('private.pem', 'w') as file:
          file.write(priv_key)
  