Python で空文字列 "" とブール値の真か偽のメモ

(python2.7)

$ ipython

In [1]: def check(val):
   ...:         if val:
   ...:                 return True
   ...:         else:
   ...:                 return False
   ...:

In [2]: check("")
Out[2]: False

In [3]: check("" and True)
Out[3]: False

In [4]: check("" and False)

Out[4]: False

In [6]: check((not "") and True)
Out[6]: True

In [7]: check((not "") and False)
Out[7]: False