input: Write a function to generate an RSA public/private key pair and save them in files named 'public.pem' and 'private.pem' respectively.
  assert generate_key_pair() == None
output: 
  from cryptography.hazmat.primitives.asymmetric import rsa
  from cryptography.hazmat.primitives import serialization
  
  def generate_key_pair():
      private_key = rsa.generate_private_key(
          public_exponent=65537,
          key_size=2048,
      )
      public_key = private_key.public_key()
  
      with open("private.pem", "wb") as f:
          f.write(private_key.private_bytes(
              encoding=serialization.Encoding.PEM,
              format=serialization.PrivateFormat.PKCS8,
              encryption_algorithm=serialization.NoEncryption()
          ))
  
      with open("public.pem", "wb") as f:
          f.write(public_key.public_bytes(
              encoding=serialization.Encoding.PEM,
              format=serialization.PublicFormat.SubjectPublicKeyInfo
          ))
  