input: Write a python function to find the most expensive item in a list of dictionaries using a lambda function.
  assert most_expensive_item([{'name': 'apple', 'price': 10}, {'name': 'banana', 'price': 5}, {'name': 'cherry', 'price': 15}]) == {'name': 'cherry', 'price': 15}
  assert most_expensive_item([{'name': 'pen', 'price': 1.5}, {'name': 'notebook', 'price': 3}, {'name': 'eraser', 'price': 0.5}]) == {'name': 'notebook', 'price': 3}
  assert most_expensive_item([{'name': 'shoe', 'price': 50}, {'name': 'shirt', 'price': 20}, {'name': 'jeans', 'price': 40}]) == {'name': 'shoe', 'price': 50}
output: def most_expensive_item(items):
      return max(items, key=lambda x: x['price'])