input: Write a python function to get the top user from a list of users based on their scores and return the user as a JSON object.
  assert get_top_user([{'name': 'Alice', 'score': 10}, {'name': 'Bob', 'score': 20}]) == {'name': 'Bob', 'score': 20}
  assert get_top_user([{'name': 'Charlie', 'score': 15}, {'name': 'David', 'score': 25}, {'name': 'Eve', 'score': 20}]) == {'name': 'David', 'score': 25}
  assert get_top_user([{'name': 'Frank', 'score': 30}]) == {'name': 'Frank', 'score': 30}
output: def get_top_user(users):
      top_user = max(users, key=lambda user: user['score'])
      return top_user