Thanks to everyone who responded with valuable suggestions. I appreciate them all. I found the exact reason why "import" command fails.
At the beginning I created my script file with MS Notepad. After studying all the advice, I realized that I did not try other text editors just becuase the tutorial says: "use your favorite text editor to create a file called fibo.py in the current directory with the following contents:" Then I created another file with the same stuff in it using WordPad. The behaviour of the "import" command improved a lot but still not good. Then I used MS-DOS' text editor to create the same file. Immediately the "import" command worked as it was supposed to. Almost. "fibo.fib2(100)" command stil does not work. This is fine: >>> fibo.fib(1000) 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987 This not fine: >>> fibo.fib2(100) [1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89] When I enter "fibo.fib2(100)", I get the following: >>> fibo.fib2(100) Traceback (most recent call last): File "<stdin>", line 1, in ? File "C:\Python24\fibo.py", line 11, in fib2 while b < n: UnboundLocalError: local variable 'b' referenced before assignment This is fine: >>> fibo.__name__ 'fibo' >>> fib=fibo.fib >>> fib(500) 1 1 2 3 5 8 13 21 34 55 89 144 233 377 Both Python2.4 and 2.5 are behaving the same. I will also try to create the file with Vi editor. -- http://mail.python.org/mailman/listinfo/python-list