python 从字典中提取子集

prices = {
 'ACME': 45.23,
 'AAPL': 612.78,
 'IBM': 205.55,
 'HPQ': 37.20,
 'FB': 10.75
 }

p1 = {key: value for key, value in prices.items() if value > 200}

tech_names = {'AAPL', 'IBM', 'HPQ', 'MSFT'}
 p2 = {key: value for key, value in prices.items() if key in tech_names}