:file:`{prefix}` and :file:`{exec-prefix}` stand for the directories that Python is installed to, and where it finds its libraries at run-time. They are always the same under Windows, and very often the same under Unix and Mac OS X. You can find out what your Python installation uses for :file:`{prefix}` and :file:`{exec-prefix}` by running Python in interactive mode and typing a few simple commands. Under Unix, just type ``python`` at the shell prompt. Under Windows, choose :menuselection:`Start --> Programs --> Python X.Y --> Python (command line)`. Once the interpreter is started, you type Python code at the prompt. For example, on my Linux system, I type the three Python statements shown below, and get the output as shown, to find out my :file:`{prefix}` and :file:`{exec-prefix}`::