邏輯運算子

1. 邏輯(logical)運算子，主要用在組合判斷狀況。

   pyuser@deyu ~/zzz$ python
   Type "help", "copyright", "credits" or "license" for more information.
   >>> x=7
   >>> x<10 and x>5
   True
   >>> x<5 or x>10
   False
   >>> not(x<5 or x>10)
   True
   >>> quit()