75-19:~ loewis$ python Python 2.3.5 (#1, Mar 20 2005, 20:38:20) [GCC 3.3 20030304 (Apple Computer, Inc. build 1809)] on darwin Type "help", "copyright", "credits" or "license" for more information. >>> f=open("/etc/python", "rU") Traceback (most recent call last): File "", line 1, in ? IOError: [Errno 2] No such file or directory: '/etc/python' >>> f=open("/etc/passwd", "rU") >>> f >>> f.readline() '##\n' >>> def fib(n): ... assert n >= 0 ... if n==0 or n==1: return 1 ... return fib(n-1)+fib(n-2) ... >>> fib(5) 8 >>> fib(-5) Traceback (most recent call last): File "", line 1, in ? File "", line 2, in fib AssertionError >>> 75-19:~ loewis$ cat fib.py def fib(n): if n <=1 : return 1 return fib(n-1)+fib(n-2) assert fib(0)==1 assert fib(1)==1 assert fib(5)==8 assert fib(10)==20 75-19:~ loewis$ python fib.py Traceback (most recent call last): File "fib.py", line 8, in ? assert fib(10)==20 AssertionError