Unless we want to call this application with a particular version of Python (i.e., 2.4 or 2.5), we need to begin the program with the "bang" line, telling the computer where to find Python. So make this or something similar the first line of the program:
#!/usr/bin/env python
I am working on a Linux system (most web servers are Apache on Unix/Linux) and therefore use that file structure. The command 'env' invokes an execution environment according to the argument you give it; here it is 'python', and the first Python interpreter in your execution path will be used. Note that, if you use the CGI version of the RSS Reader, the bang line will need to read as follows (without quotes): '#!/usr/bin/python'. CGI requires the interpreter to be called directly.
Depending on your server's setup, you may at times want to tweak this so a different Python interpreter is called. For example, if we use Python 2.5's new 'with' statement but Python 2.5 is not the first interpreter in our path, we will need to specify that Python 2.5 is to be used. We would do this by changing the above line as follows:
#!/usr/local/bin/python2.5