a = {"hello" : "world", "cat":"bat"}
# Trying to achieve this
# Form a new dictionary only with keys with "hello" and their values
b = {"hello" : "world"}
# This didn't work
b = dict( (key, value) if key == "hello" for (key, value) in a.items())
关于如何在字典理解中包含条件表达式以决定是否应将键元组值包含在新字典中的任何建议