input: Write a python function to create a User instance and return the user's name.
  assert create_user("Alice") == "Alice"
  assert create_user("Bob") == "Bob"
  assert create_user("Charlie") == "Charlie"
output: def create_user(name):
      class User:
          def __init__(self, name):
              self.name = name
  
      user = User(name)
      return user.name