input: Write a function to classify items into predefined categories.
  assert classify(['shirts', 'pants', 'hats', 'coats']) == {'shirts': 'shirts', 'pants': 'pants', 'coats': 'coats'}
  assert classify(['dresses', 'pants', 'gloves']) == {'dresses': 'dresses', 'pants': 'pants'}
  assert classify(['shirts', 'dresses', 'coats', 'scarves']) == {'shirts': 'shirts', 'dresses': 'dresses', 'coats': 'coats'}
output: def classify(items):
      predefined_categories = {'shirts', 'pants', 'coats', 'dresses'}
      return {item: item for item in items if item in predefined_categories}